A Comparative Study of the Recurrence Rate in Hypofractionated versus Conventional Postmastectomy Radiation in Breast Cancer

Abstract

Background: Treatment options available for breast cancer are Surgery [Breast conservation surgery (BCS) or Modified radical mastectomy (MRM)]; Radiation treatment [Conventional radiation treatment or CRT and Hypofractionated radiation treatment or HRT] and Chemotherapy. In the postmastectomy or post lumpectomy setting, radiotherapy (RT) improves loco-regional control. CRT for breast includes 50 Gy in 25 fractions (2 Gy per fraction) and HRT includes 42.5 Gy in 16 fractions (2.7 Gy per fraction) or extreme hypofractionation like 26 Gy in 5 fractions. Alpha/beta value for breast is less, so HRT is ideal for breast. So, there will be good loco-regional control, without increased normal tissue damage. This study aims to identify recurrence rate and toxicity in breast cancer patients treated using conventional and hypofractionated postmastectomy radiotherapy among Indian population. Primary objective: To assess recurrence rate of disease in breast cancer patients treated using hypofractionated postmastectomy radiation and to compare it with breast cancer patients treated using conventional postmastectomy radiation. Secondary objective: To assess the toxicity in hypofractionation and conventional fractionation arm. Methods: This is a prospective observational study conducted in Department of Radiation Oncology from December 2017 to June 2019. Radically treated breast cancer patients who received radiation treatment either conventional or hypofractionated as one of the treatment modalities were included in the study. Data were collected using a structured proforma, history and physical examination, master file of the patients, lab results and the imaging reports, written informed consent form, ECOG performance status scale (Eastern Cooperative Oncology Group), RTOG (Radiation Therapy Oncology Group) Acute Radiation Morbidity Scoring Schema. Patients were monitored for 18 months to identify recurrence rate and toxicity in each arm. Results and discussion: A total of 241 patients were enrolled into this study, among them 175 patients (73%) were given hypofractionation radiotherapy and 66 patients (27%) were given conventional radiotherapy. In hypofractionation arm, recurrence was found in 14 patients (8%), of which, 3 were local recurrences [chest wall] and 11 were systemic recurrences, while in conventional arm, recurrence was found in 4 patients (6%) and all of them were systemic recurrences. Recurrence rate in hypofractionation arm was 8% and in conventional arm was 6.10%. The Kaplan Meier curve shows no significant difference between the two arms with p value = 0.76. Acute toxicities assessed were dermatitis, esophagitis and pneumonitis. Among acute dermatitis, 4 patients had grade 3 and 2 patients had grade 4 in hypofractionation arm, while in conventional arm, 7 patients had grade 3 and 1 patient had grade 4. Grade 1 and 2 together versus grade 3 and 4 acute dermatitis showed a statistically significant difference between the two arms, with more acute toxicity in the conventional arm. Among acute esophagitis, 1 patient had grade 3 and no patients had grade 4 in hypofractionation arm; while in conventional arm, no grade 3 and grade 4 acute esophagitis were found. Among acute pneumonitis, 2 patients had grade 3 and 1 patient had grade 4 in hypofractionation arm, while in conventional arm, 1 patient had grade 3 and no patients with grade 4 were found. Grade 2 and grade 3 acute lung toxicities were found in patients with central lung distance more than 1.5 cm. Conclusion: It was found that the recurrence rate of hypofractionation radiotherapy was comparable to conventional fractionation radiotherapy. With respect to acute dermatitis, grade 1 and grade 2 were significantly more in conventional than hypofractionation arm. Hypofractionated radiotherapy is an equally effective option to conventional radiotherapy and should be encouraged, especially for developing countries like India where the resource is limited, and the incidence of tumour is high.