Delayed Adjuvant Chemotherapy in Older Women with Breast Cancer May Be Associated with Worse Survival

A study published in Cancer Medicine suggested that delays in adjuvant chemotherapy are associated with worse survival in older patients with breast cancer.

Given this finding, researchers indicated that providers should avoid delays and begin chemotherapy no later than 90 days after surgery, regardless of the patient’s breast cancer subtype or age.

“This data should encourage providers to take appropriate steps to ensure timely initiation of chemotherapy,” the authors wrote.

Using the SEER-Medicare and Texas Cancer Registry-Medicare databases, the researchers identified patients aged 66 years or older diagnosed between 2001 and 2015 with localized or regional breast cancer. Time from surgery to chemotherapy (TTC) was categorized into 4 groups, including 0 to 30 days, 31 to 60 days, 61 to 90 days, and more than 90 days.

Among the 28,968 women included in the study, the median TTC was 43 days. Overall, 5-year overall survival (OS) estimates by TTC group were 0.82 in the 0- to 30-day group, 0.81 in the 31- to 60-day group, 0.90 in the 61- to 90-day group, and 0.74 in the 90-day or more group (P < .001). Breast cancer-specific survival showed a similar trend (P < .001). Notably, only 10.7% of patients experienced TTC greater than 90 days.

Importantly though, older age, black or Hispanic race/ethnicity, unmarried status, more comorbidities, hormone receptor-positivity, mastectomy, Oncotype DX testing, and full state buy-in were all associated with an increased risk of delay.

“Given the worse survival outcomes associated with adjuvant chemotherapy delays, providers should engage proactively other members of their patients’ multidisciplinary care teams to coordinate diagnostics and treatment modalities efficiently,” the authors noted. “It is possible that delays with increasing age are associated with concerns about older patients’ ability to tolerate chemotherapy without significant adverse events.”

Moreover, chemotherapy delay was associated with worse OS (HR, 1.33; 95% CI, 1.25-1.40) and breast cancer-specific survival (HR, 1.39; 95% CI, 1.27-1.53).In a subgroup analysis, delayed chemotherapy was associated with worse OS and breast cancer-specific survival among those with hormone receptor-positive (HR, 1.56; 95% CI, 0.97-2.51), HER2-positive (HR, 1.99; 95% CI, 1.04-3.79), and triple-negative (HR, 2.15; 95% CI, 1.38-3.36) tumors.

“These findings suggest that among patients with highly proliferative tumors, the optimal time window to start adjuvant chemotherapy is narrower,” the authors explained. “However, our study still demonstrates a time-dependent survival benefit even among patients that received chemotherapy [more than] 90 days after surgery.”

Ultimately though, the researchers indicated that this study was limited by the variables available within the databases used. Specifically, delays in diagnosis and delays in initiating adjuvant endocrine therapy or distance from the patient’s home to the nearest hospital could not be accounted for. In addition, the investigators indicted that it is possible that longer follow-up could reveal that delays in TTC have a more pronounced survival impact in patients with hormone receptor-positive breast cancer where recurrence trends tend to follow a longer course compared to HER2-positive breast cancer and triple-negative breast cancer.

“Despite these limitations, our study provides an in-depth evaluation of the impact of treatment delays in a vulnerable population,” the authors wrote.

Reference:

Smith-Graziani D, Lei X, Giordano SH, Zhao H, Karutui M, Chavez-MacGregor M. Delayed initiation of adjuvant chemotherapy in older women with breast cancer. Cancer Medicine. doi: 10.1002/cam4.3363.