Functional decline and resilience in older adults over the age of 70 receiving radiotherapy for breast cancer: A pilot study

Introduction: Radiotherapy (RT) as an adjuvant, post-lumpectomy treatment has been shown to improve local control and survival in people with breast cancer. While adverse events because of cancer treatments are common, many older adults have demonstrated the ability to return to their baseline levels of physical functioning. There are limited reports on the functional decline and recovery of older patients undergoing RT. The primary objective of this study was to investigate physical function at various time points during RT in people with breast cancer over age 70 and their ability to recover post-decline. Materials and Methods: Seventy-nine patients with breast cancer aged 70+ undergoing adjuvant RT at Sunnybrook Health Science Centre, Toronto, Ontario, Canada were enrolled for a prospective observational study. Participants completed the EORTC QLQ-C30 quality of life questionnaire before their first RT, after their final RT, and at three- and six-months post-RT to assess changes in physical function. Descriptive statistics were utilized to evaluate EORTC QLQ-C30 scores. A higher score was indicative of poorer physical function. Physical decline was a 10+ point increase in EORTC QLQ-C30 score from baseline to the last RT, and resilience was a return to <10 points from the baseline score within six months post-RT. Resistance was a post-RT change from the baseline score by fewer than 10 points. Results: Nine patients (11%) experienced physical decline following their last RT, and two of them (22%) displayed resilience within six months. There were no demographic or symptom variables associated with functional decline from the baseline to post-RT, nor with resilience. Nausea, pain, and diarrhea post-RT were associated with functional decline at six months post-RT (P = 0.0185, P = 0.0449, P = 0.0007, respectively). Nausea and diarrhea at baseline were associated with resistance to decline (P = 0.0055, P = 0.019, respectively), and with decline at the six-month follow-up (P <= 0.0001, P = 0.0235, respectively). Discussion: This study highlights the incidence of physical decline in patients over age 70 receiving RT for breast cancer and identifies risk factors for decline. Future research with a larger sample, longer follow-up period, and incorporating geriatric assessments pre-RT is warranted to better understand functional decline and resilience in this population.