An in-house self-held respiration monitoring device (SHRMD) was developed for providing deep inspiration breath hold (DIBH) radiotherapy. The use of SHRMD is evaluated in terms of reproducibility, stability and heart dose reduction.

Sixteen patients receiving radiotherapy of left breast cancer were planned for treatment with both a free breathing (FB) scan and a DIBH scan. Both FB and DIBH plans were generated for comparison of the heart, left anterior descending (LAD) artery and lung dose. All patients received their treatments with DIBH using SHRMD. Megavoltage cine images were acquired during treatments for evaluating the reproducibility and stability of treatment position using SHRMD.

Compared with FB plans, the maximum dose to the heart by DIBH technique with SHRMD was reduced by 29·9 ± 15·6%; and the maximum dose of the LAD artery was reduced by 41·6 ± 18·3%. The inter-fractional overall mean error was 0·01 cm and the intra-fractional overall mean error was 0·04 cm.

This study demonstrated the potential benefits of using the SHRMD for DIBH to reduce the heart and LAD dose. The patients were able to perform stable and reproducible DIBHs.

During the radiation therapy of tumoral breast, the contralateral breast (CB) will receive scattered doses. In the present study, the photon and thermal neutron dose values received by CB surface during breast cancer radiation therapy were measured.

The right breast region of RANDO phantom was considered as CB, and the measurements of photon and thermal neutron dose values were carried out on this region surface. The phantom was irradiated with 18 MV photon beams, and the dose values were measured with thermoluminescent dosimeter (TLD-600 and TLD-700) chips for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes in the presence of physical and dynamic wedges.

The total dose values (photon + thermal neutron) received by the CB surface in the presence of physical wedge were 12·06%, 15·75% and 33·40% of the prescribed dose, respectively, for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes. The corresponding dose values for dynamic wedge were 9·18%, 12·92% and 29·26% of the prescribed dose, respectively. Moreover, the results showed that treatment field size and wedge type affect the received photon and thermal neutron doses at CB surface.

According to our results, the total dose values received at CB surface during breast cancer radiotherapy with high-energy photon beams are remarkable. In addition, the dose values received at CB surface when using a physical wedge were greater than when using a dynamic wedge, especially for medial tangential fields.

To evaluate changes of accumulated doses from an initial plan in each fraction by deformable image registration (DIR) with daily megavoltage computed tomography (MVCT) images from helical tomotherapy for prostate cancer patients.

The MVCT images of five prostate cancer patients were acquired by using a helical tomotherapy unit before the daily treatment fraction began. All images data were exported to DIR procedures by MIM software, in which the planned kilovoltage computed tomography (kVCT) images were acting as the source images with the daily MVCT acquired as the target images for registration. The automatic deformed structure was used to access the volume variation and daily dose accumulation to each structure. All dose-volume parameters were compared to the initial planned dose.

The actual median doses of the planning target volume (PTV) received 70 Gy and 50.4 Gy were decreased at the end of the treatment with an average 1·0 ± 0·67% and 2·1 ± 1·54%, respectively. As regards organs at risk (OARs), the bladder and rectum dose-volume parameters tended to increase from the initial plan. The high-dose regions of the bladder and rectum, however, were decreased from the initial plan at the end of the treatment.

The daily actual dose differs from the initial planned dose. The accumulated dose of target tends to be lower than the initial plan, but tends to be higher than the initial plan for the OARs. Therefore, inter-fractional anatomic changes should be considered by the DIR methods, which would be useful as clinically informative and beneficial for adaptive treatment strategies.

Stereotactic body radiation therapy for lung tumours can expose patients to radiation pneumonitis (RP) (<6 months after irradiation) and lung fibrosis (beyond 6 months). The aim of this study was to describe post-irradiation radiographics appearances.

This retrospective study of 90 patients with a stage I non-small cell lung carcinoma reports a detailed description of the computed tomography (CT) or positron emission tomography/CT changes that can be observed after treatment, according to modified Kimura score for RP and Koenig’s classification for fibrosis. This evaluation was realised at 1 month and then every 3–4 months, with a median follow-up of 35 months.

The most common radiological RP pattern was diffuse consolidation. It appears in a mean time of 4 months and reaches its maximum at 9 months after radiotherapy. Seventy-three per cent of the RP evolved to fibrosis. Most of these findings were encompassed in the 35 Gy isodose.

Radiological parenchymal changes are frequent in the treatment region, which renders the tumour response monitoring by tumour size, particularly by response evaluation criteria in solid tumours, unsuitable.

We sought to retrospectively report our outcomes using post-operative stereotactic radiosurgery (SRS)/stereotactic radiotherapy (SRT) in place of whole-brain radiation therapy (WBRT) following resection of brain metastases from our hospital-based community practice.

A retrospective review of 23 patients who underwent post-operative SRS at our single institution from 2013 to 2017 was undertaken. Patient records, treatment plans and diagnostic images were reviewed. Local failure, distant intracranial failure and overall survival were studied. Categorical variables were analyzed using Fisher’s exact tests. Continuous variables were analyzed using Mann–Whitney tests. The Kaplan–Meier method was used to estimate survival times.

16 (70%) were single-fraction SRS, whereas the remaining 7 patients received a five-fraction treatment course. The median single-fraction dose was 16 Gy (range, 16–18). The median total dose for fractionated treatments was 25 Gy (range, 25–35). Overall survival at 6 and 12 months was 95 and 67%, respectively. Comparison of SRS versus SRT local control rates at 6 and 12 months revealed control rates of 92 and 78% versus 29 and 14%, respectively. Every patient with dural/pial involvement at the time of surgery had distant intracranial failure at the 12-month follow-up.

Single-fraction frameless SRS proved to be an effective modality with excellent local control rates. However, the five-fraction SRT course was associated with an increased rate of local recurrence. Dural/pial involvement may portend a high risk for distant intracranial disease; therefore, it may be prudent to consider alternative approaches in these cases.

Radiotherapy is one of the treatments used to treat prostate cancer, and dose escalation to 74–78 Gy in conventional fractionation is the standard regimen. Currently, according to the hypothesis of low alpha/beta ratio in prostate cancer cells, using hypo-fractionation has been reported in many publications with promising results. This retrospective study was designed to evaluate the implementation of a moderate hypo-fractionation regimen in high-risk prostate cancer in our division.

Between 2012 and 2017, 40 patients with high-risk, localised prostate cancer were treated by a moderate hypo-fractionation regimen (70 Gy at 2·5 Gy per fraction) with intensity-modulated radiation therapy. The data related to treatment outcomes and toxicities were evaluated.

The mean PSA at diagnosis was 86·2 ng/mL (95% CI 49·9–122·4). Thirty-eight patients received long-term hormonal therapy. Fifty-two percent had a Gleason score of 8–10, and 65% had an initial PSA >20 ng/mL. The mean doses (in EQD2) to the D50% of PTV, D2% of organs at risk (bladder, rectum and bowels) were 80, 78·3, 76·4, and 50·2 Gy, respectively. Two patients had biochemical recurrence during the follow-up period.

A moderate hypo-fractionation regimen (70 Gy at 2·5 Gy per fraction) is feasible. Our experience found that this regimen yields tolerable, acceptable toxicity profiles in high-risk, localised prostate cancer patients.

Breast cancer patients referred for external beam radiotherapy and who have large and/or pendulous breasts can present positioning and immobilisation challenges. Deep infra-mammary and/or lateral wrap skin folds can occur that can lead to unwanted radiation-induced skin toxicity. The purpose of the study was to evaluate the immobilisation techniques adopted for this subgroup of patients in order to inform best practice.

A survey aimed to identify the current clinical practice in radiotherapy centres throughout the United Kingdom and Ireland was undertaken. The email survey was distributed with support of the Radiotherapy Services Managers group.

Twenty-six of the 74 radiotherapy centres responded to the survey. Responses demonstrated that supine positioning with or without additional immobilisation was preferable. Of the eight different immobilisation techniques identified, patients positioned supine on a breast board wearing a bra was the most common. Only two of the centres reported using a prone technique.

Immobilisation and reproducibility are key for successful external beam radiotherapy particularly when advanced treatment techniques are being employed. No single technique gained widespread acceptance as the optimum for the effective immobilisation of patients with large and/or pendulous breasts. Further evaluative research in the form of a multi-centre trial is warranted in order to clearly establish the most effective immobilisation methods/devices for this ever expanding, subgroup of cancer patients.

The purpose of this study was to estimate technical treatment accuracy in fractionated stereotactic radiosurgery (fSRS) using the Extend™ system (ES) of Gamma Knife (GK).

The fSRS with GK relies on a re-locatable ES where the reference treatment position is estimated using repositioning check tool (RCT). A patient surveillance unit (PSU) monitors the head and neck movement of the patient during treatment and imaging. The quality assurance test of RCT was performed to evaluate a standard error (SE) associated with a measurement tool called digital probe. A ‘4-mm collimator shot’ dose plan for a head–neck phantom was investigated using EBT3 films. CT and MR distortion measurement studies were combined to evaluate SEimaging. The combined uncertainty from all measurements was evaluated using statistical methods, and the resultant treatment accuracy was investigated for the ES.

Four sets of RCT measurements and 20 observations of associated digital probe showed SERCT of ±0·0186 mm and SEdigital probe of ±0·0002 mm. The mean positional shift of 0·2752 mm (σ = 0·0696 mm) was observed for 20 treatment settings of the phantom. The differences between radiological and predefined isocentres were 0·4650 and 0·4270 mm for two independent experiments. SEimaging and SEdiode  tool were evaluated as ±0·1055 and ±0·0096 mm, respectively. An expanded uncertainty of ±0·2371 mm (at 95% confidence level) was observed with our system.

The combined result of the positional shift and expanded uncertainty showed close agreement with film investigations.

To compare the dosimetric results regarding the sparing effect on normal tissue between RapidArc (RA) and helical tomotherapy (HT) plans for nasopharyngeal carcinoma (NPC) patients in cases of the equal target dose controls utilising two techniques.

Thirteen NPC patients treated with HT were replanned using the Varian Eclipse treatment planning system (TPS) for the RA plan. The target dose of the RA plan was optimised equally to the HT plan in terms of target coverage, dose conformity (CI) and dose homogeneity (HI) for assessing the normal tissue sparing between two techniques. All dose–volume parameters monitor units (MUs) and delivery time were also investigated.

All dosimetric parameter comparisons of organs-at-risk (OARs) between the RA and HT plans were not significantly different for brain stem, spinal cord and cochlea. However, the RA plan showed a significantly lower dose to the left parotid gland. The mean and median dose were significantly lower in the RA plan versus the HT plan by p-value 0·005 and 0·039, respectively. The MUs and delivery time were also significantly lower in the RA plan with a p-value of 0·00.

With the same planning target volume coverage, homogeneity and conformity, almost all of RA and HT treatment planning met the planning goal for normal tissue sparing. There were no significant differences between the two techniques except in the left parotid gland. The RA plans were superior to HT plans by effectively reducing the MUs and treatment time.

In the treatment of locally advanced head and neck cancer (LA-HNC), both dose escalation and hypo-fractionation can improve tumour control rates with uncertain role of addition of concurrent chemotherapy. We aimed at developing a new radiotherapy protocol for patients not eligible to receive the standard concurrent chemo-radiation therapy (CCRT) with little toxicity profile.

A total of 63 LA-HNC patients were randomised to receive either: 70 Gy in 35 fx in 7 weeks concurrently with cisplatin 100 mg/m2 every 3 weeks for 3 doses (Arm A) or 74 Gy in 33 fx in 6·5 weeks (Arm B). Volumetric modulated arc therapy plans were created for both treatment arms. We compared the local control (LC), progression-free survival (PFS), overall survival (OS) and acute and late toxicity between the two arms.

A total of 33 patients were in Arm A versus 30 patients in Arm B with median follow-up 24·2 months. No significant differences in LC, PFS and OS between the two arms. Complete remission occurred in 54·5 and 63·3% of patients in Arms A and B, respectively. All toxicities were significantly less in Arm B than Arm A.

Slightly dose-escalated hypo-fractionated regimen is safe and feasible and has comparable efficacy and less acute and late side effects than conventional dose CCRT with avoidance of chemotherapy-related toxicities in LA-HNC patients.

The purpose of this study is to investigate the feasibility of proton arc therapy (PAT) using the double-scattering MEVION-S250 proton system. The treatment planning and dose delivery parameters from PAT were compared with conventional treatment planning techniques.

PAT was simulated with multiple conformal and fixed-aperture beams (5–15) using the MEVION-S250-double-scattering proton system. Conformal apertures were simulated with the Eclipse-treatment-planning system: (a) using a static single aperture that provides the best average conformal circular or rectangular apertures to cover the tumour from different angular views (SPAT), and (b) dynamic conformal apertures of the tumour shape at each irradiation angle that can be obtained from a multi-leaf-collimator system (DPAT).

The DPAT and SPAT plans provided superior dose coverage and sparing of normal tissues in comparison with conventional plans (CPT). The entrance normal tissue and skin doses (<40%) were lowered significantly by delivering dose from different directions over a wider angular view compared to conventional plans that have large entrance dose from only two fields. While the mean and minimum doses from PAT and CPT were comparable, the maximum doses from arc plans were lower than the maximum doses in conventional plans. The SPAT and DPAT plans had comparable dose parameters for regularly shaped targets. The heterogeneity index (HI) was superior in PAT plans which improved with increasing number of beams in arc plans for the different treatment sites. The conformality index (CI) depends on the treatment site and complexity of the shape of the planning target volume where for brain, pancreatic and lung tumours, PAT plans conformality was comparable and sometimes superior to CPT; and HI and CI were generally better in DPAT compared to SPAT.

PAT plans have superior dose coverage and sparing of normal tissues compared to CPT plans using the MEVION double-scattering system as shown in this simulation study. Ideally, conformal proton arcs require beam shaping and dose delivery with the gantry moving; however, the MEVION double-scattering system lacks a multi-leaf collimator system and cannot deliver dose during gantry rotation. The single aperture conformal proton therapy technique is more time and cost effective compared with conventional techniques that are used currently with the MEVION proton therapy system because of the elimination of the need for patient-specific compensators. In present study, PAT was simulated with the MEVION double-scattering proton therapy system; however, it can be performed also with other proton therapy systems.

In this study, the differences between calculated and measured dose values were then analysed to assess the performance, in terms of accuracy, of the tested treatment planning system (TPS) algorithms applied to calculate electron beam dose targeted and non-targeted the breast region.

The beryllium oxide (BeO) dosimeters placed on the female RANDO phantom were irradiated 12 MeV electron energy with medical linear accelerator and repeatedly read in the Risø thermoluminescence (TL)/optically stimulated luminescence (OSL) system via OSL method at least three times.

For electron treatment, one made quantitative comparisons of the dose distributions calculated by TPSs with those from the measurements by OSL at various points in the RANDO phantom.

The mean dose measured from the dosimeters placed on the female RANDO phantom target left breast region was 160 cGy and non-target right breast region was 1·2 cGy. Analysis of Generalised Gaussian Pencil Beam (GGPB) and Electron Monte Carlo (eMC) algorithms for determined region mean point dose values, respectively, 174 and 164 cGy. Two algorithms for non-targeted region calculated same point dose values of 0·2 cGy.

The results of this study showed that BeO dosimeters can be used with OSL method in radiotherapy applications and it is a very important tool for the determination of targeted/non-targeted absorbed dose.

The main objective of this study is to assure the quality of cervical cancer treatment plans using an electronic portal imaging device (EPID) in RapidArc techniques.

Fifteen cases of cervical cancer patients undergoing RapidArc technique were selected to evaluate the quality assurance (QA) of their treatment. The computed tomography (CT) of each patient was obtained with 3-mm-slice thickness and transferred to the Eclipse treatment planning system. The prescribed dose (PD) of 50·4 Gy with 1·8 Gy per fraction to planning target volume (PTV) was used for each patient. The aim of treatment planning was to achieve 95% of PD to cover 97%, and dose to the PTV should not receive 105% of the PD. All RapidArc plans were created using the AAA algorithm and treated on Varian DHX using 6 MV photon beam, with two full arcs. Gamma analysis was used to evaluate the quality of the treatment plans with accepting criteria of 95% at 3%/3 mm.

In this study, maximum and average gamma values were 2·53 ± 0·409 and 0·195 ± 0·059 showing very small deviation and indicating the smaller difference between both predicted and portal doses. Gamma Area changes from > 0·8 to > 1·2. SD increased to 5·4% and mean standard error increased to 4·67%.

On the basis of these outcomes, we can summarise that the EPID is a useful tool for QA in standardising and evaluating RapidArc treatment plans of cervical cancer in routine clinical practice.

Concurrent chemoradiation is the definitive treatment for advanced cervical cancer. Pelvic radiation is known to damage the adjacent normal tissues thereby causing acute toxicities. The modern conformal radiation techniques like three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy are known to reduce the toxicities and improve clinical outcomes.

To retrospectively evaluate the frequency and severity of acute toxicities encountered during concurrent chemoradiation of locally advanced cancer cervix treated with 3D-CRT.

The medical case records of 174 cervical cancer patients treated between November 2015 and November 2018 were studied. One hundred and thirteen histologically proven locally advanced cancer cervix patients (Stage IIB–IIIB) treated with concurrent 3D conformal chemoradiation between were included in the study. Patients received 46 Gy in 23 fractions with concurrent weekly cisplatin (40 mg/m2) on days 1, 8, 15 and 22 of radiation. The study endpoints were treatment-related toxicities which were graded according to CTCAE version 5.0.

One hundred and thirteen patients were analysed for the study. Gastrointestinal toxicity was the predominant toxicity observed followed by haematological toxicity. 31·7% patients reported grade 1–2 diarrhoea and 39·7% reported grade 1–2 leucopenia. None of the patients reported grade 3 or higher toxicities. Treatment interruptions were noted due to these toxicities.

Concurrent chemoradiation is the definitive treatment for locally advanced carcinoma cervix with acceptable toxicities. Proper management measures should be undertaken for these toxicities to avoid treatment interruptions and ensure better treatment compliance.

The aim of this study was to produce a low-cost anatomical model of adult male including lower limbs to evaluate the three-dimensional dose distribution for dosimetry measurements, especially in total body irradiation (TBI) and total skin electron therapy (TSET).

Computed tomography (CT) scan images of the atomic energy organisation RANDO phantom and lower limb CT scan images of 20 healthy persons were averaged. Selections of different body tissues substitute materials and phantom validation were performed according to previous studies worked on construction of radiation therapy phantoms.

The dosimetry aspect of the selected substitute materials from all considered methods showed that they were in good agreement with real human tissue, especially bone, with a percentage error of 0·5%. The results show that the electron densities obtained from the linear attenuation coefficient (reDLAC) for the tissue equivalent material used in the phantom is a better option for validation.

This validated phantom has numerous advantages over the origin type of RANDO phantom. Therefore, using it in TBI and TSET dosimetry is recommendable.

While treating brain metastasis with whole-brain radiotherapy incorporating a simultaneous integrated boost (WBRT-SIB), the risk of hippocampus injury is high. The aim of this study is to compare dosimetrically between intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in sparing of hippocampus and organs at risk (OARs) and planning target volume (PTV) coverage.

In total, 16 patients presenting with more than one brain metastases were previously treated and then retrospectively planned using VMAT and IMRT techniques. For each patient, a dual-arc VMAT and another IMRT (five beams) plans were created. For both techniques, 30 Gy in 10 fractions was prescribed to the whole brain (WB) minus the hippocampi and 45 Gy in 10 fractions to the tumour with 0·5 cm margin. Dose–volume histogram (DVH), conformity index (CI) and homogeneity index (HI) of PTV, hippocampus mean and maximum dose and other OARs for both techniques were calculated and compared.

A statistically significant advantage was found in WB-PTV CI and HI with VMAT, compared to IMRT. There were lower hippocampus mean and maximum doses in VMAT than IMRT. The maximum hippocampus dose ranged between 15·5 and 19·2 Gy and between 18·4 and 20·6 Gy in VMAT and IMRT, respectively. The mean dose of the hippocampus ranged between 11·5 and 17·7 Gy and between 13·2 and 18·3 Gy in VMAT and IMRT, respectively.

Using WBRT-SIB technique, VMAT showed better PTV coverage with less mean and maximum doses to the hippocampus than IMRT. Clinical randomised studies are needed to confirm safety and clinical benefit of WBRT-SIB.

Pelvic wall control and toxicity was retrospectively assessed in patients who received individually customised parametrial boost (PMB) for locally advanced cervical cancer with 2D planned external beam radiotherapy. Outcomes of a dose-escalated combined boost were also evaluated.

Toxicity and pelvic wall recurrence was evaluated over a median period of 24 months between two groups who received different pelvic wall doses. One group was randomised to receive either intracavitary brachytherapy (ICRT) with an external beam PMB using a customised midline shield, or a dose-escalated combined boost with interstitial brachytherapy (ISBT) and PMB. The comparator group received no PMB.

At 24 months, pelvic wall recurrence occurred in 2/112 and 40/130 with and without PMB, respectively (p < 0·000001). No significant difference in toxicity was noted between boost versus no-boost groups (p = 0·56). Combined ISBT/PMB dose escalation showed no significant difference in pelvic wall recurrence compared with PMB alone (p = 0·49).

Individually customised 2D PMBs with 3D image-based ICRT was safe and improved pelvic wall control in locally advanced cervix cancer. Dose-escalated combined boosts offered no significant benefit over standard boost doses.

The head and neck cancers as a whole are the most common cancers among males in India. Technological advancements have led to an improvement in radiation therapy (RT) techniques with subsequent reduction in normal tissue complications. To correct patient set-up errors, an off-line correction method like no action level (NAL) protocol may be used as a preferred protocol particularly for a busy department. The objectives of the study were to measure the translational set-up errors using kV cone-beam computed tomography (CBCT) in patients undergoing intensity modulated radiotherapy (IMRT) in head and neck cancers and also to optimise clinical target volume (CTV) to planning target volume (PTV) margin using NAL protocol.

On the first 5 days of RT, patient’s position was verified by kV-CBCT and then weekly during the course of treatment. The comparison between the reference and kV-CBCT images was performed, and the shifts measured and recorded. The mean error from the initial five consecutive fractions was corrected on the sixth daily fraction. Displacements in all the directions were measured. The population systematic and random errors were determined and used to estimate PTV margins according to the van Herk formula.

A total of 322 images were analysed. Before correction, 15, 12 and 9% patients had systematic error ≥3 mm on X, Y and Z axes, but after correction this was reduced to 9, 0 and 0%. The total percentage of patients whose set-up margin was ≥5 mm before correction was 5, 6·25, 3·75%, but after correction it reduced to 1·88, 0, and 0·63%. The margins of total population were reduced to 63, 65 and 56% after correction on X, Y and Z axes, respectively.

A simple off-line NAL protocol can correct the set-up errors without daily on-line imaging in patients undergoing IMRT and hence acting as a resource sparing alternative. Five millimetre margin to CTVs was adequate and safe to overcome the problem of set-up errors in head and neck IMRT.

Metastatic brain disease is still a major contributor to cancer treatment failure. Various treatments have improved in the recent decades, which allow for better control of brain metastatic lesions. Various prognostic scoring tools have been developed and used worldwide to stratify patients with brain metastases to determine who will benefit most from aggressive treatment. The three most commonly used prognostic scoring tools are recursive partitioning analysis (RPA), basic score for brain metastases (BSBM) and graded prognostic assessment (GPA). The aim of this study is to validate these scoring tools using an Indonesian cancer patient population.

A retrospective analysis of all patients presenting with brain metastases from January 2012 until December 2014, through using hospital medical records, was conducted. All patients receiving whole brain radiotherapy during this period were included in this study. A follow-up with a telephone call was carried out to determine the patient’s health and survival status. Uncontactable patients were excluded from the analysis. Survival analysis was carried out by stratifying patients based on the three prognostic scoring systems.

A total of 80 patients were eligible to be included in the study, with 18 excluded due to being uncontactable. The remaining 62 patients’ data were analysed and stratified with all three scoring systems. The RPA was found to confer better stratification than BSBM and GPA in our study population.

GPA was non-prognostic in our study population and BSBM was less prognostic, especially in the middle group, class 1 and class 2. Those BSBM class 1 and class 2 did not provide good prognostic stratification in our study population, whereas RPA was proven to be the best in stratifying patients’ prognosis with brain metastases in our study population.

To determine the frequency, factors and reasons of patient non-adherence to radiotherapy (RT) in a tertiary cancer centre.

Inadvertent treatment interruptions often lead to prolongation of planned treatment time. In the case of RT with a curative intent, prolongation of planned treatment has been associated with inferior clinical outcomes. Delay or prolongation of treatment is associated with a relative risk of local recurrence by up to 2% per day for specific malignancies. Thus, it is critical to understand key factors that influence non-adherence to RT.

A retrospective observation audit was conducted comprising patients treated with radical, adjuvant or palliative RT at our centre from January 2018 to December 2018. Non-adherence was defined as premature permanent termination of planned treatment by the patient without recommendation or consultation from the treating clinician. All data were collected and analysed (retrospectively) with the help of Statistical Package for the Social Sciences (SPSS) version 22.

A total of 1,548 patients were included in the study of which 105 (6·7%) were non-adherent to planned RT. Of the total 105 patients, 44 (42%) were elderly (60 years and above). Treatment non-adherence was predominant in males (male:female = 1·85:1). More than 90% of non-adherent patients had stage III and IV cancer. A total of 77 patients (74%) out of 105 were more than 50 km away from our centre. A total of 66 (63%) out of 105 patients had completed more than 2 weeks of radiation (40% of planned RT) and then defaulted for radiation due to acute toxicities.

Treatment adherence is a major factor in determining successful outcomes among cancer patients treated with RT. This study reveals several factors that contribute to non-adherence to treatment.