Background/Aims: Mastectomy and breast conserving surgery followed by radiotherapy are considered initial guideline therapies for early stage breast cancer with randomized trials demonstrating reduced risk of recurrence. However, older women and those with comorbidities frequently receive only breast conserving surgery. The interaction of age and comorbidity with breast cancer severity and their impact on receipt of guideline therapy have not been well studied.
Methods: In the population-based BOW cohort of 1837 women age=65 years receiving initial treatment for early stage breast cancer in 6 integrated healthcare delivery systems in 1990-1994 and followed for 10 years, we examined predictors of receiving less than guideline therapy. We also assessed the impact of less than guideline therapy on breast cancer recurrence stratified by breast cancer severity (low, moderate, or high risk for recurrence using the 1992 St Gallen criteria).
Results: Age and comorbidity were independently associated with receipt of less than guideline therapy after controlling for breast cancer severity and race. However, compared to those at lowest risk for recurrence, women at the highest risk were unlikely to receive less than guideline therapy (odds ratio (OR) 0.31, 95% confidence interval (CI) 0.21, 0.46) while women at moderate risk were about half as likely (OR 0.55, CI 0.36, 0.85). During follow-up, 295 women had a breast cancer recurrence. Using Cox regression modeling stratified by the 3 levels of risk for recurrence, non-receipt of guideline therapy was associated with recurrence among women at moderate (HR 5.10, CI 1.93, 13.49) and even low risk (HR 3.24, CI 1.15, 9.12). The elevated hazard rate ratio was not observed for the high risk level group (HR 1.29, CI 0.78, 2.15). Age and comorbidity were not associated with recurrence in any of the analyses.
Conclusions: Among these older women with early stage breast cancer, decisions about guideline therapy appear to have partially balanced breast cancer severity against age and comorbidity. However, even among women at low risk of recurrence, omitting guideline therapy placed them at elevated risk of recurrence.