Draft Consensus Statement Presents Evidence on Ductal Carcinoma In Situ

Laurie Barclay, MD

September 24, 2009

September 24, 2009 — An impartial, independent panel of 14 experts in oncology, radiology, radiation therapy, gynecology, preventive medicine, pathology, and other fields has drafted a consensus statement summarizing the evidence regarding ductal carcinoma in situ (DCIS) and the implications of that evidence. The statement was based on a review of evidence, including systematic literature review, expert presentations, and audience input, presented at a 2-day conference that ended today.

The State-of-the-Science Conference on Diagnosis and Management of Ductal Carcinoma In Situ was held by the National Cancer Institute and the Office of Medical Applications of Research of the National Institutes of Health (NIH) at the NIH campus in Bethesda, Maryland. DCIS is also known as intraductal carcinoma and stage zero breast cancer.

"DCIS represents a spectrum of abnormal cells that happen to be contained to the breast duct, and it is a risk factor for invasive cancer, but not invasive cancer itself," Panel and Conference Chairperson Carmen Allegra, MD, associate director for clinical and translational research, Shands Cancer Center, University of Florida in Gainesville, said today during a media telebriefing. "In general, DCIS is discovered as a consequence of screening for invasive disease. Since the advent of widespread screening, the prevalence of DCIS has dramatically increased."

DCIS is the most prevalent, noninvasive tumor of the breast, typically identified during routine mammograms as microcalcifications. Because not all microcalcifications represent DCIS, however, the diagnosis must be confirmed by biopsy. Implementation of screening mammography has led to a more than 7-fold increase in incidence through the 1990s, followed by a plateau. It is estimated that by 2020, more than 1 million US women will be living with DCIS.

Natural Disease Course Unknown

The natural course of DCIS is not completely understood, because DCIS in some individuals can be contained without metastasizing or causing other problems for a long period, whereas in other patients, DCIS will progress to invasive disease. At present, it is still unknown which lesion types are more likely to become invasive.

"It is not clear how many patients with DCIS who are untreated will develop invasive cancer," Dr. Allegra said. "Given that the diagnosis has considerable emotional and physical impact, it is important to determine risk factors for progression. The panel recommends that the scientific community determine if there are identifiable subgroups leading to an algorithm for risk stratification, so that treatment would be more personal based on individual risk, rather than treating everyone the same."

Because nearly all individuals with DCIS are asymptomatic, the true prevalence is difficult to determine. However, it presently accounts for about 20% of screening-detected breast cancer. Risk factors predisposing to DCIS are similar to those for invasive breast cancer: older age, family history of breast cancer, previous biopsies, history of hormone replacement therapy, and older age at first childbirth. Among women at high risk, use of tamoxifen is associated with reduced incidence of DCIS.

Because the natural course of DCIS is not well understood and treatment benefit may depend on specific tumor and patient characteristics, the treatment of DCIS remains controversial. The most effective treatment modality may vary based on specific factors related to the tumor and to the patient, but incomplete evidence regarding optimal treatment hinders effective decision-making for clinicians and patients alike.

Magnetic resonance imaging (MRI) may assist in diagnosis, but the effect on patient outcomes is still unclear. The panel suggested that there is currently little evidence regarding the usefulness of MRI in diagnosing or managing DCIS, and they urged the scientific community to explore mechanisms by which MRI can be better used. These may include use of different pulse sequences or use of dedicated breast coils.

Prognosis for patients with DCIS is generally excellent if they are treated promptly after diagnosis, with a 10-year survival rate of 98% or better. However, data from the 1980s and 1990s suggest that in women treated with removal of the DCIS but no other therapy, the tumor recurred in 40%. Half of these recurrences were DCIS, and the other half were invasive cancers. Risk for recurrence in the contralateral breast was low.

DCIS Management Complicated

"The diagnosis and management of DCIS are extremely complicated because there are many unanswered questions, including the natural history of the disease," Dr. Allegra said. "A primary question for future research is accurate identification of subsets of patients who would not need as much therapeutic intervention without sacrificing the excellent outcomes of 98% or better survival we now see with therapy."

Depending on patient and tumor characteristics, standard DCIS therapies include breast conservation (local excision) with or without radiation, or mastectomy. For high-risk patients, sentinel lymph node biopsy may also be considered, as metastasis is often first detected in this region.

Although there is some evidence suggesting that hormone therapy such as tamoxifen may help prevent DCIS recurrence and lower the risk of developing estrogen receptor–positive breast tumors, potential adverse effects of these drugs must be carefully considered. The panel noted that the physical and emotional effects of these treatments should be weighed thoughtfully, given that there are relatively few reliable data on the comparative effectiveness of diagnostic and therapeutic options in DCIS.

Key questions addressed at the conference and summarized by the panel are as follows:

  • What are the incidence and prevalence of DCIS and of its specific pathologic subtypes? How do mode of detection, population characteristics, and other risk factors affect incidence and prevalence?

  • In patients diagnosed with DCIS, how does the use of MRI or sentinel lymph node biopsy affect important clinical outcomes?

  • How do local control and systemic outcomes in DCIS vary in subgroups based on tumor-specific and patient-specific characteristics?

  • How do surgery, radiation, and systemic treatment affect outcomes in patients with DCIS?

  • What are the most critical research questions that should be addressed regarding diagnosis and management of DCIS?

Panel discussion and audience input after the conference led to an additional question regarding the nomenclature of DCIS, the concern being that use of the word "carcinoma" may provoke undue fear in patients, given the fact that the overall prognosis is excellent and that the disease may not progress.

"In DCIS, the cells histologically and biochemically are identical to the cells in invasive carcinoma, telling us that the cells can be a precursor to invasive cancer," said Arnold M. Schwartz, MD, PhD, professor of pathology at George Washington University School of Medicine in Washington, DC. "DCIS is a spectrum of subtypes — some more indolent and others more aggressive, demanding more aggressive therapy."

The panel noted that one solution to the nomenclature dilemma is to try to improve communication between the patient and clinician regarding diagnosis, prognosis, and therapy options.

The conference was presented through the NIH Consensus Development Program. The systematic literature review on DCIS was prepared under contract with the Agency for Healthcare Research and Quality. The Johns Hopkins University School of Medicine was the educational provider. The panel's statement is an independent report and is not a policy statement of the NIH or the federal government.

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