Trends in the use of short-course radiation therapy for rectal cancer in New South Wales, Australia.

Introduction: Trends in the use of short-course radiation therapy (RT) for rectal cancer in Australia are unknown. The purpose of this study was to compare short-course RT and long-course chemoradiation (CRT) utilisation in the neoadjuvant treatment of rectal cancer in New South Wales (NSW).

Methods: Patients who received neoadjuvant RT (2009-2014) for rectal cancer were identified from the NSW Central Cancer Registry. Univariate and multivariable analyses were performed to investigate factors associated with receipt of short-course RT.

Results: A total of 1196 (81%) patients received long-course CRT, and 274 (19%) patients received short-course RT. Receipt of short-course RT was associated with older age: 54% in patients ≥80 years, and 11% in patients <50 years (P < 0.0001). Patients with T2 disease (30%) were more likely to receive short-course RT, compared with T3 (19%) or T4 (8%) disease (P = 0.002). Patients with N0 (23%) disease were more likely to be treated with short-course RT, compared with N+ (16%) (P = 0.03). The proportion of short-course RT delivered to patients with Charlson Comorbidity Index (CCI) ≥ 2 (28%) was higher than patients with CCI = 0 (17%) (P = 0.002). There was wide variation in the proportion of short-course RT used across residence local health districts (5-29%) (P < 0.0001).

Conclusion: In rectal cancer patients treated with neoadjuvant RT in NSW, 19% received short-course RT. The use of short-course RT was associated with older age, comorbidities and less advanced disease. Wide variation across NSW was identified and future research investigating factors for the variation will be useful.