7th International Conference on Adjuvant Therapy in Primary Breast Cancer
Ductal Carcinoma In Situ
Kathleen I. Pritchard, MD and Pamela Goodwin, MD, MSc, FRCP
The management of ductal carcinoma in situ (DCIS) has garnered a lot of attention over the past few years, reflecting the increasing prevalence of DCIS. Paradoxically, the standard of care for women with early invasive breast cancer is now breast-conserving therapy, but many women with DCIS, particularly with extensive disease, undergo mastectomy.
In a session chaired by Dr. Richard Margolese, of McGill University in Montreal, Quebec, Canada, and Dr. Melvin J. Silverstein, of the University of Southern California in Los Angeles, California, some of the controversy surrounding optimal management of DCIS was addressed.
Current Management Options
Although DCIS can progress to invasive carcinoma, said Dr. William Wood of Emory University School of Medicine in Atlanta, Georgia, autopsy studies document a prevalence of DCIS that exceeds that of invasive carcinoma, suggesting that some cases do not progress and may therefore be overtreated.
The multifocality of DCIS and the fact that it does not always occur in a segmental distribution (it tends to follow duct tissue to the nipple) may also contribute to overtreatment.Dr. Wood stated that the surgical goal of DCIS treatment is to remove the entire tumor and to attempt a 1-cm margin. Smaller margins are unwise, since the smaller the margin, the higher the risk of local failure. Local failure is also related to nuclear grade and to age, with younger women associated with the greatest risk of local recurrence.
Mastectomy is associated with a less than 1% failure rate and may be indicated when disease is widespread; a skin-sparing approach can help to facilitate reconstruction. When breast-conserving therapy is performed, postoperative radiation may be necessary to reduce local failure rates. Although axillary staging is not generally recommended for DCIS, sentinel node mapping is currently under investigation.
Devising Appropriate Treatment Strategies
Dr. Wood outlined a 2-step paradigm that can be used for making treatment decisions. Step 1 should focus on tumor size and margins. A small focus of DCIS measuring less than 1 cm would be excised with no further treatment. Breast-conserving therapy could be considered for intermediate-sized foci, provided clear margins could be obtained and radiation therapy follows surgery.
For more extensive lesions, such as those more than 4 cm and those where clear margins could not be obtained, skin-sparing mastectomy with immediate reconstruction is recommended. Step 2 of the treatment paradigm dictates that these approaches be modified depending upon the age of the patient and the nuclear grade of the tumor.
For example, young women with high-grade tumors, even if they are less than 1 cm, might be offered radiation therapy following tumor excision, while older women with low-grade tumors more than 1 cm might be spared radiation. Tamoxifen could be considered as an adjunct in both scenarios.
In light of this, Dr. Silverstein suggested that modification of the Van Nuys classification of DCIS to enhance the accuracy of prediction of local recurrence may be warranted. First, age (< 40 years, 40-60 years, or more than 60 years) should be considered along with the original 3 factors of size, margin width, and tumor grade/necrosis. Second, since assessment of tumor size can be difficult without 3-dimensional reconstruction with microscopic correlation, margin width alone may provide a reasonable surrogate.
Does Tamoxifen Prevent Recurrence or Occurrence of DCIS?
Dr. Bernard Fisher reviewed the results of a series of NSABP trials, which have demonstrated the benefit of postlumpectomy radiation in women with DCIS[19,20] as well as the added benefit of tamoxifen in reducing not only the risk of ipsilateral recurrence but also contralateral breast cancer occurrence. The study authors concluded that tamoxifen should be offered to all women with DCIS.
However, Dr. Margaret Spittle, of the University College Hospital in London, England, presented data from a UK trial which did not identify a reduced risk of either ipsilateral recurrence or contralateral occurrence when tamoxifen was administered after breast-conserving therapy with radiation for DCIS. Thus, the role of tamoxifen in DCIS requires further clarification.
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