Approximately 40% of patients treated with anthracyclines are still not receiving National Comprehensive Cancer Network (NCCN) guideline–adherent prophylaxis for chemotherapy-induced vomiting. In most cases, guideline nonadherence was secondary to the lack of a neurokinin 1 (NK1) antagonist.
Patients on highly emetogenic chemotherapy should receive prophylaxis in the form of a 5-HT3 antagonist in combination with steroids and an NK1 antagonist, according to Mariana Chavez-MacGregor, MD. The addition of an NK1 antagonist was incorporated into the NCCN and American Society of Clinical Oncology guidelines in 2006.
“Patients receiving highly emetogenic chemotherapy, and also selected moderately emetogenic regimens commonly used in the treatment of breast cancer, should receive this prophylaxis to relieve their nausea and vomiting, starting with the first dose of the first cycle of chemotherapy,” said Chavez MacGregor, assistant professor in the division of cancer prevention at the University of Texas MD Anderson Cancer Center in Houston.
Chavez-MacGregor and her colleagues conducted a population-based study to evaluate adherence to antiemesis prophylaxis guidelines among breast cancer patients treated with anthracyclines and presented their findings at the 2015 Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology International Symposium on Supportive Care in Cancer.
The regimens evaluated in the study included AC (Adriamycin [doxorubicin] + cyclophosphamide), TAC (docetaxel + Adriamycin + cyclophosphamide), and FAC (5FU + Adriamycin + cyclophosphamide). “These are considered to be third-generation regimens equivalent in efficacy,” noted Chavez-MacGregor.
Breast cancer patients treated with AC, FAC, or TAC were identified from 2 data sources: (1) population-based cancer registries linked to Medicare claims (SEER [Surveillance, Epidemiology, and End Results]/TCR [Texas Cancer Registry]), which included 5569 patients aged >65 years, and (2) a private insurance claims database (MarketScan), encompassing 25,971 patients aged <65 years.
Antiemetics given with the first dose of the first cycle of chemotherapy were recorded. “We wanted to look only at the first dose of chemotherapy, since the administration of antiemetics in the second dose may be influenced by the patient’s experience with the first cycle,” she said.
Adherence to NCCN guidelines was determined based on the guideline in effect during the treatment year.
Guideline-adherent prophylaxis was observed in 22.4% of SEER/TCR-Medicare patients and 28.2% of MarketScan patients. There was a dramatic decrease in guideline adherence in 2006 (the year that the guidelines incorporated the use of NK1 antagonists), with an increase in subsequent years.
Guideline nonadherence after 2006 was secondary to the lack of NK1-antagonist use in 82.7% and 83.3% of the cases in SEER/TCR and MarketScan, respectively.
“We saw a slow but continuous increase in guideline adherence, and by 2013, close to 60% of patients younger than 65 were receiving triple therapy with their first cycle of chemotherapy,” she said.
In the older patient population, investigators observed that the year of treatment and the time between diagnosis and chemotherapy initiation were negatively associated with guideline-adherent treatment. In the younger cohort, the same results were observed.
Of the roughly 30,000 total patients evaluated, 85% were treated with AC. “We observed that when compared to patients receiving AC, those receiving TAC or FAC were even less likely to receive guideline-adherent treatment,” noted Chavez-MacGregor. “Similarly, compared to patients younger than 40, those that were older were less likely to receive guideline-adherent treatment.”
The researchers concluded that most patients treated with anthracyclines do not receive guideline-adherent prophylaxis, and in most cases this is secondary to lack of NK1-antagonist use.
Variation in adherence according to year reflects slow uptake of changes made in the guidelines, particularly among elderly patients. “However, it is important to note that by 2013, 60% of patients were receiving triple therapy,” said Chavez-MacGregor. “It is very likely that the current rate is even higher.”
Chavez-MacGregor M, He W, Zhao H, et al. Antiemesis prophylaxis among breast cancer (BC) patients receiving anthracyline-based chemotherapy: a population-based study. Presented at: 2015 Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology International Symposium on Supportive Care in Cancer; June 25-27, 2015; Copenhagen, Denmark. Abstract 11-02-O.