HOUSTON, Dec. 11 (UPI) — Breast cancer patients who delay chemotherapy for more than 90 days after surgery are one-third more likely to die within five years, and those with triple-negative breast cancer who delay treatment have a more than 50 percent increased risk of death, according to a new study.
Chemotherapy is used after surgery to prevent remnants of tumors from growing or becoming drug-resistant. Although most patients start treatment within 30 to 40 days of surgery, and the Centers for Medicare and Medicaid services considers starting within 120 days to be a “quality metric,” researchers said there previously had not been a recommended time frame for starting.
The researchers suggest not putting off chemotherapy treatment at all after surgery, though factors such as socio-economic status and insurance coverage can delay treatment.
“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 Dr. Mariana Chavez Mac Gregor, an assistant professor at the University of Texas, in a press 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.”
Using data from the California Cancer Registry, researchers analyzed records for 24,843 people with stage 1 to 3 invasive breast cancer diagnosed between 2005 and 2010 who were treated with chemotherapy after surgery.
The median time to chemotherapy, or TTC, for all patients was 46 days. The researchers found no evidence of adverse outcomes for those with TTC of 31 to 60 days, or 60 to 90 days.
The 9.8 percent of patients in the study who waited 91 or more days to start chemotherapy were 34 percent more likely to die within five years and 27 percent more likely to die from breast cancer in five years as compared with patients who started treatment within 30 days of surgery.
Among individual cancers, triple-negative breast cancer was was linked to a 53 percent increase in risk of death, but there was no effect seen in patients with hormone-receptor-positive breast cancers.
Worse overall survival was seen among black patients, those with a lower socio-economic status, and people using Medicare and Medicaid. Patients with later stage and more serious types of cancer had fewer delays, however.
“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,” Chavez Mac Gregor said. “In most clinical scenarios, administering chemotherapy within three months is more than feasible.”
The study is published in JAMA Oncology.
