Upper limit of radiation treatment portals in rectal cancer: is it wise to keep using bony landmarks in the present era of 3D conformal treatment?

Background: This study aimed to compare the levels of L5-S1 interspace and the bifurcation of common iliac vessels on simulation images of rectal cancer patients to evaluate the adequacy of superior borders in conventional 2D planning for covering internal iliac vessels. Materials and methods: Simulation images of 236 rectal cancer patients who received neoadjuvant chemoradiation and surgery were analyzed. The images were retrieved from the radiation treatment database and included delineations of L5-S1 interspace and common iliac vessel bifurcation. Distances between these landmarks were measured. Results: Among the 236 patients, the majority had the common iliac artery bifurcation positioned above the L5-S1 interspace. Specifically, 78.3% of patients had the right common iliac bifurcation above L5-S1 interspace, with an average distance of 2.02 cm. For the left common iliac artery, 77.11% of patients had the bifurcation above L5-S1 interspace, with an average distance of 1.99 cm. Notably, there were cases where the bifurcations were not at the same level. Conclusion: Using the L5-S1 junction as the upper border of the treatment portal may result in missing proximal nodes at risk of metastases. However, further research is needed to determine the significance of failures above the L5-S1 interspace for justifying the inclusion of the common iliac artery bifurcation in the treatment portal.

Efficacy of adjuvant radiation in early-stage cancers of buccal mucosa: an institutional experience.

PURPOSE: The purpose of this study is to determine if depth of infiltration is the only risk factor that will determine the outcomes in early-stage buccal mucosa patients or do the other minor risk factors have an impact too. METHODS: It is a retrospective analysis of 226 patients with early-stage buccal mucosa cancer who were treated with curative intent from 2010 to 2020. These patients were grouped in two arms, surgery alone (n = 111) and surgery followed by adjuvant radiotherapy (n = 115). Patients were followed up and local and regional recurrences and distant metastasis were recorded. RESULTS: Our results show that addition of radiation to the standard surgery arm improves overall survival and disease-free survival, though the improvement in overall survival was not statistically significant. This improvement was more pronounced in the depth of infiltration > 5 mm and in 5 mm or less depth of infiltration this benefit was not statistically significant. Other factors like perineural invasion, lymphovascular invasion, tumour size, node positive, margin positive were considered for univariate analysis. Although there was a trend towards improvement of OS and DFS, it was not statistically significant as far as these factors are concerned. CONCLUSION: The role of adjuvant radiation in early-stage cancers of buccal mucosa is a crucial tool with definitive DFS benefit and requires more prospective trials to answer the OS benefit.

A comparative study evaluating the dose volume parameters in 3D conformal radiation of left sided whole breast irradiation including regional lymphnodes - a need of resource constrained countries.

BACKGROUND: The purpose of this study was to compare four 3D conformal radiation techniques in treatment of left breast cancer patients. MATERIALS AND METHODS: Radiation was planned for 20 patients to the left breast and regional lymph nodes using four techniques: partially wide tangents, photon-photon mix, photon-electron mix and 30/70 photon-electron mix. All plans were evaluated for internal mammary nodes (IMN) coverage, hotspot and normal tissue constraints. RESULT: The 85% of planning target volume (PTV) coverage was lesser for upper IMN than the lower IMN (below the lower border of the clavicular head) for all four techniques. The lower IMN coverage was better for partially wide tangent (80.46%) and photon-photon mix (88.88%). The lowest value of hotspot was seen in the partially wide tangent technique (112.69% ± 1.92). Hotspot is unacceptably high in both photon-electron mix and 30/70 photon-electron mix (> 120%). Left lung mean dose for all techniques on a pair-wise comparison showed no statistical difference. Left lung V20 values for partially wide tangent was 37.56% ± 8.17 and for photon-photon mix it was 40.49% ± 3.36. The mean heart dose with partially wide tangent was 9.43 ± 3.15 Gy and with photon-photon mix it was 10.10 ± 2.70 Gy. The mean heart dose for photon-electron mix was 7.56 ± 1.95 Gy and for 30/70 photon-electron mix it was 7.98 ± 2.16 Gy. CONCLUSION: No single technique satisfies all the criteria. The decision should be made on a case-by-case basis, considering the anatomy of the patient, availability of electron facilities and setup accuracy and reproducibility.