Is Postmastectomy Radiation Necessary for All Breast Cancer Patients?

From Medscape Medical News
Roxanne Nelson

March 11, 2010 — Some women with early-stage breast cancer that has spread to only 1 lymph node might not derive a benefit from postmastectomy radiation, according to new data presented during the plenary session at the Society of Surgical Oncology (SSO) Annual Cancer Symposium in St. Louis, Missouri.

Researchers from the University of Texas M.D. Anderson Cancer Center in Houston found that after surgery, adjuvant chemotherapy, and/or hormonal therapy, the risk for local regional recurrence rates were extremely low for patients with T1 and T2 breast cancer with 0 to 3 positive lymph nodes.

At a median follow-up of 94 months (95% confidence interval [CI], 88 to 94), local regional recurrence occurred in only 2.13% (n = 22) of the total number of patients in the study. There was also no statistical difference in the recurrence rates between patients with 1 lymph node metastasis and those with no nodal involvement (3.3% vs 2.1%).

Radiation is indicated for women after a lumpectomy because it reduces the recurrence rate, but the data are less clear after mastectomy, explained senior author Henry Kuerer, MD, PhD. professor and training program director in M.D. Anderson's Department of Surgical Oncology.

Data Could Be Outdated

"We have long-term data, but they are old data," he told Medscape Oncology in an interview. "They are from randomized studies that were conducted in the 1960s to 1980s, and the rates of local regional recurrence were high in these women. A benefit was seen with radiation."

Dr. Kuerer pointed out that in 2005, a meta-analysis of trials conducted in the 1960s to 1980s showed that there was a 66% reduction in locoregional recurrence in women who received postmastectomy radiation, compared with no radiation. The analysis also showed a small survival benefit associated with radiation therapy.

These findings led to a shift in clinical practice, and the National Comprehensive Cancer Network altered their guidelines in 2007 to suggest that stage I and II breast cancer patients with 1 to 3 lymph node metastases "strongly consider" radiation after mastectomy.

The overall 5- and 10-year recurrence rates in those studies ranged from 20% to 25%, which are much higher than what is currently observed, said Dr. Kuerer. "We have not seen that in our own clinical practice."

We have better screening, better detection, better surgical techniques.
In the decades since those studies were conducted, Dr. Kuerer explained, much has changed in the treatment and diagnosis of breast cancer. "We have better screening, better detection, better surgical techniques, and we now have therapies that didn't exist when these early studies were done," he said. "Pathology has also improved, and more extensive examination of lymph nodes is now conducted."

Radiotherapy after mastectomy is effective at decreasing the chances of local regional recurrence in patients with lymph node spread in more than 4 nodes, and where the risk for recurrence is greater than 15%. "The benefit of radiation therapy in this case clearly outweighs the risk, and can offer a survival advantage," he said.

But the use of radiation in patients with early-stage breast cancer with only 1 to 3 positive nodes has been a "hot topic of debate" within the cancer community, Dr. Kuerer explained.

Low Recurrence Rates

The goal of this study was to determine the present-day rates of local regional recurrence to better gauge the potential benefit of postmastectomy radiation in this particular subpopulation of breast cancer patients. Dr. Kuerer and his colleagues conducted a retrospective study in which they evaluated the clinical and pathological factors of 1022 stage I or II breast cancer patients who received a mastectomy at M.D. Anderson between 1997 and 2002.

The median patient age was 55 years and, within this group, 79% had T1 and 21% had T2 tumors. The majority of patients (74%) had no lymph node metastasis, but 26% had 1 to 3 positive nodes. None of the patients in the study received postmastectomy radiation therapy or neoadjuvant therapy, and 77% received adjuvant chemotherapy and/or hormonal therapy.

Node Status and Rates of Local Regional Recurrence (LRR) Number of
Positive Nodes n (%) 5-Year LRR 10-Year LRR
0 753 (74) 1.2% 2.4%
1 180 (18) 2.4% 3.2%
2 69 (7) 3.1% 6.7%
3 21 (2) N/A N/A


There were too few patients in the study with 3 positive nodes to determine rates. Patients who were younger than 40 years, who had T2 tumors with nodal metastasis, and who had estrogen-receptor negative tumors had significantly higher chances of local regional recurrence (P < .01).

"I think that our study should have an impact on how women with early-stage disease and 1 positive lymph node are treated," said Dr. Kuerer, although he cautioned that treatment decisions must always be based on the individual patient.

Monica Morrow, MD, chief of the breast service in the Department of Surgery at Memorial Sloan-Kettering Cancer Center in New York City, doesn't believe that current practice should change just yet.

"The question asked in this study — what is the rate of local recurrence after mastectomy in patients receiving modern systemic therapy and high-quality surgery — is an important one," said Dr. Morrow, who moderated the plenary session at the SSO symposium. However, "this study cannot be used as evidence that radiation therapy can be eliminated, because this was a very selected group of patients."

This study should stimulate other more inclusive studies, but should not be regarded as practice-changing.
She told Medscape Oncology that there were many more patients who received treatment during the same time period, and who received radiation therapy and neoadjuvant chemotherapy, or both. "We don't have any information on how the group who didn't get radiation therapy compares or what percentage of patients they were," she explained. "So this study should stimulate other more inclusive studies, but should not be regarded as practice-changing."

Dr. Kuerer agreed that more studies are needed, and pointed to the international randomized SUPREMO trial, which is currently enrolling patients. The trial is designed to evaluate the role of chest-wall radiation therapy after mastectomy in women who are at intermediate risk for locoregional recurrence, with 1 to 3 involved lymph nodes.

"However," he said, "it may be a decade before we have that information."

Society of Surgical Oncology's Annual Cancer Symposium: Abstract 47. Presented March 6, 2010.