Acute Pharyngo-oesophagitis During Three Dimensional Conformal Radiotherapy [3-D CRT] of Chestwall/Breast is Predictable Using Dose Volume Histogram parameters V3, V4, V5 and Mean Dose of Oesophagous: A Retrospective Clinico-dosimetric Study
Background Acute Pharyngo-oesophagitis though a known complication of irradiation in breast cancer is less described in literature. A retrospective study was carried out to identify acute pharyngo-oesophagitis in breast cancer patients receiving adjuvant radiotherapy and to correlate it with probable patient, tumor and dosimetric[treatment]variables. Methods and Materials Seventy two patients of carcinoma breast who received adjuvant radiotherapy to chestwall/breast,axilla,,supraclavicular lymphnode region by 3-D CRT in conventional fractionation consecutively were identified for the study. Oesophagous was contoured on individual planning computed tomography images and different dosimetric parameters were calculated from dose volume histogram retrospectively. Variables of patient, tumor and treatment related attributes were analyzed with respect to acute pharyngo-oesophageal [PE] toxicity by suitable statistical tests using Statistical Package for Social Sciences [SPSS] version 20. Results and Statistics Study subjects included 71 females and one male of median age 45.5 years [range20-74 years]. Adjuvant External Beam Radiotherapy [EBRT] was delivered to chestwall in 67% patients, whole breast followed by tumor bed boost in 26% patients and bilateral chestwall were irradiated in approximately 7% patients. Acute pharyngo-oesophagitis of any grade was found in 44 patients[61%].Grade-1 PE toxicity occurred in 51% patients while grade-2 PE toxicity was noted in approximate 10% of patients. Age of patient, laterality of tumor, hormone/human epidermal growth factor receptor 2 status,target volume[chestwall versus whole breast],chemotherapy[Anthracycline/taxane],position of neck[midline versus rotated],total delivered dose,volume of oesophagous,duration of radiotherapy were not found to be related to appearance of acute pharyngo-oesophageal[PE] toxicity with statistical significance. Binary logistic regression analysis suggested maximum dose, mean dose to oesophagous,V3/V4/V5 oesophagous to be related to appearance of acute PE toxicity. Receiver Operating Characteristics[ROC] curve plotting revealed mean dose to oesophagous [when 9Gy,sensitivity for appearance of toxicity 57%], V3oesophagous[when 27%, sensitivity for appearance of toxicity 59%],V5oesophagous[when 19.5%, sensitivity for appearance of toxicity 84%],V4oesophagous[when 20%, sensitivity for appearance of toxicity 86%] are credible predictors of toxicity. Conclusion Acute PE toxicity is often encountered during irradiation of chestwall/breast as part of adjuvant management of breast cancer. In the chosen cohort on retrospective analysis mean dose to oesophagous,V3/V4/V5 oesophagous were found to co-relate with radiation induced acute pharyngo-oesophagitis. These findings can be useful in estimating acute PE toxicity in chestwall/breast irradiation and can add to optimization of conformal radiotherapy planning.