Despite major studies showing that postmastectomy radiation therapy improves survival for women with high-risk breast cancer and evidence-based guidelines supporting the use of postmastectomy radiotherapy, 45% of these patients do not receive such treatment, according to an analysis of data from more than 32,000 patients with breast cancer.

“There’s a clear gap between the scientific evidence demonstrating [postmastectomy radiotherapy’s] benefits and the proper use of the therapy in everyday clinical practice,” stated Benjamin D. Smith, MD, principal investigator of the study, which was published recently in the journal Cancer.¹ Dr. Smith is Assistant Professor, Department of Radiation Oncology, at The University of Texas MD Anderson Cancer Center in Houston, and Vice Chairman of the American Society for Radiation Oncology clinical guidelines committee.

The study cites three landmark randomized controlled trials demonstrating that postmastectomy radiotherapy “decreased locoregional recurrence and improved survival among patients with high-risk breast cancer,” defined as stage T3–T4 and/or N2–N3.^2-4 Previous research had shown that publication of these studies increased postmastectomy radiotherapy in these patients, and the recent study was intended to determine whether the use of postmastectomy radiotherapy has increased in response to evidence-based guidelines. The researchers looked at data from 38,322 women aged ≥ 66 who underwent invasive breast cancer between 1992 and 2005. The percentage of patients with high-risk breast cancer who received postmastectomy radiotherapy increased from 36.5% to 57.7% between 1996 and 1998, when the landmark clinical trials were published. “However no further increase in [postmastectomy radiotherapy] use was observed between 1999 and 2005 despite publication of multiple guidelines endorsing its use; during this period, only 54.8% (2,729 of 4,978) of high-risk patients received [postmastectomy radiotherapy],” the authors reported.

The investigators used data for women 66 and older because more complete data—combined Surveillance, Epidemiology and End Results (SEER)-Medicare data—exists for these women, Dr. Smith told The ASCO Post. “With the SEER-Medicare data, you can look at claims for receipt of radiotherapy, so you can be relatively confident that you know who received radiation,” Dr, Smith said, “but the chief limitation of this data set is that it only allows you to look at women who are Medicare beneficiaries,” he said. “I would love to know what utilization rates are for women in their 30s, 40s, and 50s, but the only population-based data available with which to do that is the SEER data. SEER data systemically underreports use of radiation, so I don’t think you can really do this study with just the SEER data.”

Reasons for Nonadherence

The authors offered several explanations for lack of adherence to evidence-based guidelines published by ASCO, NCI, and the National Comprehensive Cancer Network. The possible reasons include inadequate access to radiation resources, patient preference not to undergo radiation, passive rather than active dissemination of the guidelines, and gray areas where the guidelines may be open to interpretation.

“A specific subgroup within the study had larger tumors that were node-negative, T3N0, and in those patients there is some controversy about when radiotherapy is recommended,” Dr. Smith explained. “Some literature suggests that in patients who are just barely T3, with 5.5- or 6-cm tumors, if cancer has not spread to any lymph nodes and if there are no adverse prognostic factors, radiation is not always needed. But for the vast majority of patients with T3 breast cancer, radiation is recommended. If you had a smaller tumor, but had four or more involved lymph nodes, we would definitely recommend radiotherapy, and all the guidelines would concur with that. Or if you had a bigger tumor, but just one positive lymph node, again we would recommend radiotherapy, and all the guidelines would agree with that.”

Postmastectomy radiotherapy may be appropriately contraindicated in certain patients. “Radiation would be contraindicated if a patient had received prior radiotherapy for lymphoma or for a prior breast cancer, and then had a new breast cancer and a mastectomy, but that area of the chest wall and lymph nodes had previously received radiotherapy. That would be the main absolute contraindication,” Dr. Smith explained, noting that such patients were excluded from the study. Other relative contraindications, he said, include serious collagen vascular diseases like scleroderma or active lupus, and perhaps severe pulmonary disease.

Increasing Compliance

The authors offered specific strategies to increase compliance with postmastectomy radiotherapy guidelines. “Some of the suggestions we offered were attempts to include failsafe mechanisms in patient record systems,” Dr. Smith said. “It might be a care pathway or a checklist, or if you are using an electronic medical record, when you put the stage in for the patients, then a flag pops up and asks if you remembered to refer your patient for radiation therapy.”

Other suggestions include monitoring guideline adherence through internal audits and adding postmastectomy radiotherapy as an additional quality measure to the American College of Surgeons Commission on Cancer or the National Quality Forum. “Thousands of hospitals across the county participate in the American College of Surgeons Commission on Cancer. Hospitals want to be accredited by this entity because they feel it reflects well on the quality of care that they offer,” Dr. Smith noted. “They can use that accreditation as they seek to maintain and establish their market share and the viability of their hospitals.”

Payers could use financial incentives to influence adoption of guidelines. “Pay for performance hasn’t really disseminated widely. It hasn’t permeated the health-care climate now, but there are lots of very smart people interested in figuring out how they can tweak the financial incentives for physicians to help promote quality of care,” Dr. Smith said. “Some sort of pay for performance will continue to trickle into the health-care system over the next decade, and we would advocate that if it trickles into breast cancer care, this would be a good treatment to incentivize, because it is known to be effective and it appears to be underused currently.” ■

Disclosure: Dr. Smith reported that his group has received research funding from Varian Medical Systems.

SIDEBAR: Expect Questions from Your Patients

SIDEBAR: Higher Postmastectomy Radiotherapy Rates at NCCN Institutions

References

1. Shirvani SM, Pan I-Wen, Buchholz TA, et al: Impact of evidence-based clinical guidelines on the adoption of postmastectomy radiation in older women. Cancer. June 27, 2011 (early release online).

2. Overgaard M, Hansen PS, Overgaard J, et al: Postoperative radiotherapy in high-risk premenopausal women with breast cancer who receive adjuvant chemotherapy. Danish Breast Cancer Cooperative Group 82b Trial. N Engl J Med 337:949-955, 1997.

3. Ragaz J, Jackson SM, Le N, et al: Adjuvant radiotherapy and chemotherapy in node-positive premenopausal women with breast cancer. N Engl J Med 337:956-962, 1997.

4. Overgaard M, Jensen MB, Overgaard J, et al: Postoperative radiotherapy in high-risk postmenopausal breast-cancer patients given adjuvant tamoxifen: Danish Breast Cancer Cooperative Group DBCG 82c randomised trial. Lancet 353:1641-1648, 1999.