A new study led by scientists at The University of Texas MD Anderson Cancer Center provided evidence suggesting that delaying the start of adjuvant chemotherapy by over 90 days after surgery can considerably increase the risk of death for patients with breast cancer, especially those with triple-negative breast cancer (TNBC). Researchers also reported that factors like socio-economic status, insurance coverage, and ethnicity play a role in delayed treatment. The study, in the December issue of JAMA Oncology, is titled “Delayed Initiation of Adjuvant Chemotherapy among Patients with Breast Cancer.”
Adjuvant chemotherapy, a post-primary surgery care, has been shown to decrease the chances of cancer recurrence and increase survival rates. Delaying the start of adjuvant chemotherapy can allow remnants of the tumor to grow or become resistant to drugs. While there are currently no guidelines regarding the optimal time to initiate treatment, The Centers for Medicare & Medicaid Services (CMS) considers administering adjuvant chemotherapy within 120 days of diagnosis for certain patients a quality metric, and 11 cancer hospitals, including MD Anderson, have adopted this metric.
To clarify the treatment’s optimal timing and identify factors that may contribute to a delay, the research team analyzed data from the California Cancer Registry comprising 24,823 patients with stage 1 to 3 invasive breast cancer, diagnosed between Jan. 1, 2005, and Dec. 31, 2010, who have received adjuvant chemotherapy. This study is considered the largest to date to investigate the effects of delayed chemotherapy initiation with current treatment regimes.
“Compared to patients starting chemotherapy in the first month after surgery, we observed that those who initiated chemotherapy between 30 and 90 days following surgery did not have adverse outcomes,” said the study’s lead author, Dr. Mariana Chavez Mac Gregor, assistant professor at Health Services Research and Breast Medical Oncology, in a MD Anderson’s news release. “However, starting chemotherapy more than 90 days after surgery was associated with a statistically significant increase in the risk of death and breast cancer-specific death.”
The study found that patients who started chemotherapy more than 90 days after surgery (9.8% of the study population) were 34% less likely to survive another five years, and that patients with TNBC who delayed treatment had a 53% higher risk of dying from breast cancer, in comparison to patients who initiated chemotherapy within 30 days after surgery. No significant effect from a delay was found among patients with hormone-receptor-positive (HER2-positive) breast cancers.
“These data suggest that timely initiation of chemotherapy is particularly important among patients with triple-negative breast cancer,” said the study’s senior author, Dr. Sharon Giordano, professor and chair of Health Services Research and professor at Breast Medical Oncology.
Researchers also assessed factors possibly at work in chemotherapy administration to identify patient groups in need of higher-standard care delivery. “We need to identify the determinants of delays in treatment so we can act on them and potentially improve the delivery of care in vulnerable populations. In most clinical scenarios, administering chemotherapy within three months is more than feasible,” said Dr. Chavez Mac Gregor.
The team found that while patients with later stage disease progression and TNBC were less likely to experience delays, increased age, reconstructive surgery, and certain socio-demographic factors were linked to postponed treatment. “We observed, not surprisingly, that socio-demographic factors determined, in great part, some of this delay. Patients with low socio-economic status (SES), those without private insurance, and those of Hispanic or African-American descent were more likely to have delays in their treatment,” Dr. Chavez Mac Gregor said.
Patients of African-American descent, lower SES, and Medicare and Medicaid coverage were associated with worst overall survival. But those receiving care at National Cancer Institute-designated cancer centers, when compared to those treated elsewhere, were found to have a 34% decreased risk of death.
Based on their findings, researchers concluded that chemotherapy initiation should be included as a quality metric, and that adjuvant chemotherapy treatment should begin within 90 days after surgery or 120 days of diagnosis, even though the authors recognized the retrospective nature of their study could be somewhat limiting.
“We need to start chemotherapy in a timely manner,” concluded Dr. Chavez Mac Gregor. “In those patients who want to delay their chemotherapy, I share this data and let them know that a delay can dilute the benefits of treatment. If at all possible, we should not delay.”