Patients with one of the most common and curable forms of breast
cancer may be undergoing radiation therapy unnecessarily, according
to a University of Southern California (USC) study published in the
May 13, 1999, issue of The New England Journal of Medicine.
The study, headed by Melvin J. Silverstein, MD, medical director of
the Harold E. and Henrietta C. Lee Breast Center at the USC/Norris
Comprehensive Cancer Center, examined ductal carcinoma in situ
At present, DCIS accounts for as many as 40% of new breast cancer
cases diagnosed by mammography, and estimates suggest that
approximately 40,000 new cases of DCIS will be diagnosed in 1999 in
the United States. Of these patients, 70% to 80% are eligible for
lumpectomy rather than mastectomy, but opinion on whether radiation
therapy is necessary for all DCIS patients who choose lumpectomy is
Margin Widths Govern Need for Radiation Therapy
In the article, Dr. Silverstein, a surgical oncologist, and his
colleagues found that radiation therapy does not appear to benefit
patients in whom the margin width is 10 mm or more. Wide margin
width makes complete excision more likely, said Dr.
Silverstein. Since DCIS is a noninvasive cancer that does not
spread, complete excision should cure the patient. These findings
will have important ramifications for thousands of women with the
disease. These data suggest that radiation therapy may not be the
best option for some subgroups of patients with DCIS who choose to
preserve their breast.
The USC data, which were derived from an analysis of 469 patients
choosing breast preservation, suggest that eradication of the cancer
can be achieved when margin widths are sufficiently wide. For the
purposes of the study, tumors were divided into three groups by
margin width: close or involved (< 1 mm), intermediate (1 to <
10 mm), and wide (³ 10 mm).
The fact that there were only 3 recurrences among 133 patients
with 10 mm or greater margins makes it unlikely that radiation
therapy could have any significant impact on this subgroup,
said Dr. Silverstein.
When the margin widths are less than 10 mm, radiation therapy should
remain a treatment option. The benefit of radiation therapy increases
as the margin width decreases, so that patients in whom the margin
width is less than1 mm benefit the most from postoperative radiation
therapy. In the intermediate margin width subgroup, there was an 8%
reduction in local recurrence when postoperative radiation therapy
was used, but the trend was not statistically significant, he said.
Redefining Patients Who Benefit From Radiation Therapy
Part of the controversy over treatment for DCIS stems from the fact
that to date only one prospective, randomized study has been
publishedprotocol B-17, conducted by the National Surgical
Adjuvant Breast and Bowel Project (NSABP). That study strongly
advocates excision plus radiation therapy for all patients with DCIS
who elect to preserve their breast. This is a recommendation that Dr.
Silverstein and colleagues consider too broad. It is like
treating every patient with an infection with antibioticsit
simply isnt necessary, said Dr. Silverstein.
In defense of the NSABP, its trial was designed more than 14
years ago. At that time, researchers were asking a single broad
question: Does radiation therapy benefit patients with ductal
carcinoma in situ treated with breast preservation? The answer to
that question is clearly, yes. However, the NSABP study was not
designed to answer the more sophisticated and discriminating
questions we ask today of exactly which subgroups might benefit from
radiotherapy and by how much. If the benefit in a given subgroup is
small, the advantage gained by radiation therapy will probably be
more than offset by its cost and side effects, he said.
Doctors must weigh the benefits of radiation therapy, in terms of a
decrease in local recurrence, against the side effects,
complications, inconvenience, and cost of radiation therapy. Dr.
Silverstein argues that for many women, the small or nonexistent
benefits are not worth the drawbacks, and he urges all patients with
DCIS who are considering radiation therapy to seek a second opinion.
Integrated Teamwork in Specialized CentersBest Treatment
Closely integrated teamwork is the key to complete excision of DCIS.
To achieve sufficiently wide margins, breast cancer surgery is best
performed by an integrated, experienced team including a surgeon,
pathologist, and radiologistwith long-term follow-up by a team
consisting of a radiologist, surgical, and medical oncologist, said
More than 90% of DCIS cases are found by mammography. This cancer is
not palpable or visible in the operating room. The initial
excision offers the best chance to remove the cancer with adequate
margins while achieving the best possible cosmetic result. At
USC, we use multiple guide wires in surgeries to localize all DCIS
lesions followed by complete and sequential tissue processing,
said Dr. Silverstein. Its very difficult to remove a DCIS
and achieve an adequate margin using a single wire, which is the
current standard throughout the United States.
The balance between adequate margins and a good cosmetic result
is a difficult one to achieve, he said. Although most of
these technologies are available in the community, they are not often
well integrated. For now, the best treatment options lies with
specialized multidisciplinary breast centers. They have the all the
resources in terms of skilled radiologists, surgeons, and
pathologists, working as an integrated team.
The current paradigm requires radiation therapy for all
patients with DCIS who elect breast preservation, said Dr.
Silverstein. This paper may change such thinking in that it
allows clinicians to identify patients for whom there will be little
or no benefit from radiation therapy.