Only 65% of women who should receive radiation subsequent to mastectomy are undergoing the recommended postmastectomy radiation therapy (PMRT), according to a new study published in the Journal of the American College of Surgeons (2015; doi:10.1016/j.jamcollsurg.2014.12.045).
Breast cancer patients who undergo a mastectomy should receive subsequent radiation treatment if their cancer has spread to four or more nearby lymph nodes.
PMRT reduces the risk of breast cancer recurrence and improves survival in patients whose cancer is locally advanced, with a pathologic stage of N2 or N3 using the American Joint Committee on Cancer (AJCC) staging system. The AJCC defines N2 cancer primarily as having spread to between four and nine axillary lymph nodes but no other organs, and N3 disease involves 10 or more axillary lymph nodes.
“My colleagues and I were quite startled by the finding that a third of patients with N2/N3 disease did not receive PMRT, which is the standard of care,” said lead author Quyen D. Chu, MD, MBA, FACS, professor of surgery at Louisiana State University (LSU) Health Sciences Center in Shreveport.
For this study, the investigators evaluated compliance with the treatment guidelines using the National Cancer Data Base (NCDB), a joint project of the American College of Surgeons Commission on Cancer (CoC) and the American Cancer Society.
From 2.72 million breast cancer cases diagnosed between 1998 and 2011 and listed in the database, 56,990 files of women with N2 or N3 cancer were found. The researchers evaluated these de-identified files to determine factors linked to receipt of PMRT.
Chu and colleagues used statistical analyses to find that only three factors independently predicted a higher likelihood that patients would receive PMRT: receipt of chemotherapy, readmission to the hospital within the first month after breast removal, and being alive 30 days after the operation.
Women with N2 or N3 breast cancer were 5.4 times more likely to undergo radiation therapy after mastectomy if they also received chemotherapy. In all, 82.1% of patients received chemotherapy. Chu theorized that women who chose not to receive chemotherapy might also have been unwilling to accept radiation therapy.
Breast cancer patients had 1.14 times the odds of receiving PMRT if they were readmitted to the hospital within 30 days postoperatively because of complications or other reasons. Chu suggested that hospital care providers may realize that the patient was not referred for radiation therapy, making an early readmission “a point to remedy the error” of noncompliance with treatment guidelines.
Some patients with recently diagnosed breast cancer are surprised to learn that if they undergo a mastectomy, they sometimes will need radiation therapy afterward.
Exceptions to the PMRT recommendation for high-risk breast cancers include women who had prior radiation therapy or have connective tissue disorders.