Tuesday, December 6, 2011

Mastectomy or Lumpectomy Plus Radiation: The Latest (and Longest) Study

Women with breast cancer have two surgical options - mastectomy or lumpectomy plus radiation, also known as breast conserving surgery or breast conservation therapy.

Both have pros and cons, but which is better in terms of survival and recurrence?

Today we'll share the latest (and longest) study, a 25 year follow-up of the National Cancer Institute (NCI) Breast Conservation Trial. A link to the full-text of the study, published online in Breast Cancer Research and Treatment on November 24, may be found on the Breast Conserving Surgery page of our website.

Background: Six studies found similar survival outcomes

Six major trials have compared survival rates of the two surgical options. To date, all have found lumpectomy plus radiation to be an "accepted alternative" to mastectomy with "similar survival outcomes." (Links to the various study abstracts may be found in the References section at the end of the current study.)

In addition, a meta-analysis of all six trials conducted by the Early Breast Cancer Trialist Group Collaboration "confirmed the noninferiority of breast conservation therapy compared with mastectomy," despite differences in eligibility criteria and treatment technique between trials.

The current study is one of the original six. It shares data from a 25.7 year median follow-up. It is a relatively small study, but the longest reported follow-up to date.

The NCI study design

Between 1979 and 1987, 247 women with breast tumors measuring 5cm or less were randomized to receive either lumpectomy plus radiation or a mastectomy. All women were treated with chemotherapy (Adriamycin (doxorubicin) and Cytoxan (cyclophosphamide)). After 1985, postmenopausal women with node-positive, estrogen-receptor positive breast cancer were also given tamoxifen for five years.

No difference in overall survival

Similar to the other five studies, the current NCI study demonstrated "no survival differences when comparing lumpectomy followed by whole breast irradiation versus mastectomy."

After 25 years, however, there was a "slight" survival advantage in the mastectomy group.

Predictors of decreased survival included patient age older than 50, left-sided tumors, tumor size greater than 2cm and more than 4 positive lymph nodes.

No difference in risk of metastasis

The study found "no significant difference in risk of distant metastasis" between the two arms.

High rate of recurrence in the same breast as the lumpectomy

Even though survival and metastasis rates were similar, the NCI study found a high rate of tumor recurrence in the breast treated with a lumpectomy. "More than 1 out of every 5 patients (22.3%)" in the lumpectomy group experienced a recurrence in the same breast requiring a salvage mastectomy.

The authors note that recent research suggests that same-breast recurrences may be a risk factor for decreased survival. However, in this study, even though 27 patients experienced a same-breast recurrence, there was no survival difference between the two groups.

There are several possible reasons why the rate of same-breast recurrence in this study may be greater than in the other studies.

First, the new tumor may actually be a new cancer, not a recurrence. In fact, there were 11 cancers in the opposite breast in the lumpectomy group and 15 in the mastectomy group, demonstrating that new cancers can develop over time.

In addition, the recurrence rate may be higher because this is a longer study. In fact, 3 of the recurrences occurred after a patient had been disease-free for 20 years.

Also, by design, the NCI study included women with larger tumors. The trials with lower same-breast recurrence rates included smaller-tumors and "more stringent margin evaluation." It may be that the patients in this study were already at a higher-risk of recurrence.

Long-term side effects of radiation therapy

As part of the discussion, the authors wondered if the long-term side effects of radiation might have affected survival in lumpectomy group.

A previous meta-analysis suggested "a 1.3% increase in non-breast cancer death in patients receiving radiotherapy after surgery." Although there were 5 more non-breast cancer deaths in the lumpectomy group, this trial was "not adequately powered to detect late differences in non-breast mortality."

However, left-sided cancer was "a significant predictor" of mortality. Radiation to the left-breast has been associated with cardiotoxicity in other studies. The NCI is currently conducting "extensive cardiac studies" of the 60 surviving patients in this trial.

The authors conclude that now that patients are living longer, minimizing treatment toxicity "has become a priority."

This is only the latest study on breast conserving surgery. For two-years of news and research on this and other treatment options, please visit our LATESTBreastCancer.com website. You may start exploring by clicking the Treatments tab.

As a final note, triple-negative breast cancer is a special situation. We discussed the latest research on mastectomies and lumpectomies plus radiation for triple-negative patients in our August 31 blog.

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