Breast Cancer Survival Increased by Earlier Adjuvant Chemotherapy

Breast Cancer Survival Increased by Earlier Adjuvant Chemotherapy

Mariana Chavez-MacGregor, MD

A team of researchers with the University of Texas MD Anderson Cancer Center found that adjuvant chemotherapy has a significant impact on patient survival, especially in patients with triple-negative breast cancer (TNBC).¹

The study, recently published inJAMA Oncology,²discovered that patients who began chemotherapy more than 90 days after surgery were 34% more likely to die within a 5-year time frame, and patients with TNBC faced a 53% increased risk of death than other patients with breast cancer.

No current guidelines specify the most optimal time to start adjuvant chemotherapy, which is typically given after primary surgery and has been demonstrated to reduce disease recurrence and death. According to Mariana Chavez-MacGregor, MD, lead study author and assistant professor, Health Services Research and Breast Medical Oncology, delaying the start of adjunct chemotherapy runs the risk of allowing small remnants of the tumor to either grow or become drug resistant.

Previous studies have suggested that delaying chemotherapy post surgery could cause adverse patient outcomes, but finding an optimal time frame to administer adjunct chemotherapy has not yet been identified. The Center for Medicare and Medicaid Services considers administration of the adjunct chemotherapy within 120 days of diagnosis for certain patients a quality metric.

In an effort to define a time frame, the MD Anderson team analyzed data from the California Cancer Registry and examined information from nearly 25,000 patients with stage I to III invasive breast cancer diagnosed between January 1, 2005 and December 31, 2010, who were treated with adjuvant chemotherapy.

“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 Chavez-MacGregor in a statement. “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.”

More specifically, patients who started chemotherapy treatment 90-days post surgery were 34% more likely to die within 5 years and 27% more likely to die from breast cancer within the same time period compared with patients who started their adjunct treatment within 30 days of initial surgery.

The study also found that patients with TNBC displayed a 53% increase in risk of death if adjunct chemotherapy was not administered within 90 days. Though, researchers were not able to find significant effects in delays of post-surgery treatment in hormone-receptor-positive, or HER2-positive, breast cancers.

Additionally, the MD Anderson team discovered that factors such as socio-economic status, insurance coverage, and ethnicity play a role in delayed treatment.

Patients of African-American descent, lower SES, and those with Medicare and Medicaid coverage had lower overall survival. Increased age and reconstructive surgery were also factors that contributed to delayed treatment times.

Patients with later stage disease or TNBC were less likely to experience delays in adjuvant chemotherapy.

“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 3 months is more than feasible,” said Chavez-MacGregor.

The MD Anderson team concluded that all patients with breast cancer should receive adjuvant chemotherapy either within 90 days of surgery or 120 days of diagnosis.

“In those patients who want to delay their chemotherapy, I would share this data and let them know that a delay can dilute the benefits of treatment. If at all possible, we should not delay,” Chavez-MacGregor added.

References

1. Mdanderson.org. Delaying chemotherapy in breast cancer patients reduces overall survival, especially for those with triple-negative breast cancer | MD Anderson Cancer Center. 2015. http://www.mdanderson.org/newsroom/news-releases/2015/delaying-chemotherapy-breast-patients-reduces-survival-triple-negative.html. Accessed December 13, 2015.
2. Chavez-MacGregor M, Clarke C, Lichtensztajn D, Giordano S. Delayed Initiation of Adjuvant Chemotherapy Among Patients With Breast Cancer.JAMA Oncology. 2015:1. doi:10.1001/jamaoncol.2015.3856.