SAN FRANCISCO – Injectable fulvestrant and oral anastrozole were the top picks for first-, second- and third-line treatment of metastatic breast cancer in women enrolled in Medicare Part D, based on a retrospective study of 681 women.

Total treatment costs averaged $102,000/patient, including costs for physicians, inpatient and outpatient care, hospice, skilled nursing, and durable medical equipment, reported Dr. Hope S. Rugo and her associates.

Their analysis updates a similar previous study that did not include data on oral medications. Thus, this study provides a more complete picture of treatment patterns and costs for patients with metastatic breast cancer. Oral medications now comprise three of the five most common first-, second- or third-line therapies in women who developed metastatic breast cancer, according to the researchers.

The investigators analyzed SEER (Surveillance Epidemiology and End Results) cancer registry data and Medicare data for 7,905 women who were diagnosed with breast cancer in 2001-2007 with concurrent or subsequent metastases and were enrolled in Medicare from 12 months prior to diagnosis through 2009 or death. Of these, 82% received first-line treatment. Data on oral therapies were available only for the 681 patients enrolled in Medicare Part D, the federal program that subsidizes the costs of prescription drugs for Medicare beneficiaries.

In the overall sample, 48% of the women went on to second-line therapy and 26% had third-line therapy. In the Part D subgroup, 63% went on to second-line therapy and 45% had third-line therapy, reported Dr. Rugo, director of the Breast Oncology Clinical Trials Program at the University of California, San Francisco.

The mean total cost per patient in the cohort as a whole was $127,000. Fulvestrant was the top choice for first-line therapy, used in 19%. Injectable vinorelbine was the most common second-line chemotherapy, used in 18% of those who got second-line treatment and in 16% of those who got third-line therapy, she reported in a poster presentation at a breast cancer symposium sponsored by the American Society of Clinical Oncology.

The findings were similar to those from a previous report presented by another group of investigators at the 2011 Breast Cancer Symposium. Those researchers used SEER data on women diagnosed in 2001-2005 and enrolled in Medicare until 2008 or death. Fulvestrant was most common as first-line therapy and vinorelbine was most common for second- and third-line treatment. The mean per-patient cost in that study was $110,000.

In the current analysis of the 681 patients enrolled in Medicare Part D, fulvestrant still was the most common first-line treatment given to 9.1% of patients, but oral anastrozole was a close second at 8.7%. The next most common choices were oral letrozole (7%), any taxane drug (5%), and oral tamoxifen (4%).

Of the 427 patients in the Part D subgroup who got second-line therapy, 19% received fulvestrant, 9% got anastrozole, 8% got letrozole, 7% received vinorelbine, and 4% took tamoxifen.

For third-line treatment of 309 patients in the Part D subgroup, anastrozole and fulvestrant tied for top choice (11% each), tamoxifen or letrozole was used in 7% each, and vinorelbine was used in 6%.

The total costs per drug were highest for vinorelbine: a mean of $155,000 in second-line treatment and $134,000 in third-line treatment. In comparison, mean costs for the other top second-line therapies were $111,000 for fulvestrant, $106,000 for anastrozole, $108,000 for letrozole, and $107,000 for tamoxifen. Mean costs for other third-line treatments were $110,000 for anastrozole, $100,000 for fulvestrant, $101,000 for tamoxifen, and $71,000 for letrozole.

The study excluded patients with a history of other cancers before a diagnosis of breast cancer, patients who were not eligible for Medicare Part A or Part B benefits, patients enrolled in health maintenance organizations, and those who were first diagnosed with metastatic breast cancer at the time of death or autopsy.

The data did not identify disease progression, so the investigators used a published algorithm to identify the date of metastases. They also created an algorithm to identify first-, second- and third-line treatments in the data, based on factors such as the length of time before administering a new agent. These methods may have misclassified some treatments. Other limitations of the study include using Medicare data from 2001-2007, which may not reflect recent advances in treatment. SEER data cover just 28% of the U.S. population, and 90% of the study population was 65 years in age or older, so the cohort may not be representative of all patients with metastatic breast cancer.

The symposium was co-sponsored by the American Society of Breast Disease, the American Society of Breast Surgeons, the National Consortium of Breast Centers, the Society of Surgical Oncology, and the American Society for Radiation Oncology.

Eisai funded the study and one of the investigators was an employee of the company. Dr. Rugo reported having financial associations with Merck, Novartis, and Pfizer.

sboschert@frontlinemedcom.com

On Twitter @sherryboschert

Oral therapy for metastatic breast cancer grows in Medicare patients