ORLANDO – Surgery for ductal carcinoma in situ, with or without adjuvant therapy, saves lives, asserted a breast cancer surgeon at a symposium sponsored by the Society of Surgical Oncology.
Following a surgical biopsy alone, about half of all cases of low-grade ductal carcinoma in situ (DCIS) will progress to invasive cancer within an average of 10-15 years, said Dr. Kimberly J. Van Zee, a surgical oncologist at Memorial Sloan-Kettering Cancer Center in New York.
Dr. Kimberly J. Van Zee
Additionally, without intervention, low-grade DCIS will result in death from ipsilateral invasive recurrence of breast cancer in about 18% of patients, Dr. Van Zee said.
"With treatment of DCIS, whether it’s breast conservation or mastectomy, with or without radiation, breast cancer–specific survival is over 95%," she noted.
The incidence of DCIS has increased steadily since 1975, when the rate was slightly more than 5 in 100,000 women. In 2009, the rate had reached approximately 36 in 100,000, according to Surveillance, Epidemiology, and End Results (SEER) data. The increase is probably a result of the growing adoption of screening mammography over the same period, Dr. Van Zee commented.
Treatment trends for DCIS showed a gradual but steady decline in mastectomy – from 70% in 1983 to about 28% in 1999 – and a corresponding increase in breast-conserving treatment, which increased from about 25% to 68% over the same period.
Beginning around 2005, however, there was evidence that the trend was reversing, with upticks in both mastectomy for unilateral breast cancer (J. Clin. Oncol. 2010;28:3437-41) and contralateral prophylactic mastectomy, both among women with invasive cancers and DCIS (Ann. Surg. Oncol. 2010;17:2554-62). The trends paralleled the rise in screening mammography in the United States and elsewhere in the world.
The gradual but steady decline in breast cancer deaths that began in the early 1990s appears to be attributable to a combination of increased screening mammography and improvements in adjuvant therapy, Dr. Van Zee noted, citing a 2005 study (N. Engl. J. Med. 2005;353:1784-92).
"They dissected all the various effects of treatment, incidence of screening-detected diseases, etc., and all their analyses concluded that about half of the reduction in death rate was due to screening and the other half was due to adjuvant therapy. So I think this is good circumstantial evidence that screening, with its resultant increased incidence in DCIS and the resulting increased treatment of DCIS, does result in a lower death rate from breast cancer," she said.
Further evidence comes from studies in which pathologists reviewed thousands of slides of biopsy-acquired breast tissue originally reported as benign. In each study (Cancer 1980;46[4 Suppl]:919-25; Cancer 2005;103:2481-84), the investigator identified about 30 samples with evidence of low-grade, relatively low-volume DCIS that was not recognized or treated. After 20-30 years of follow-up, half of the women had developed a clinically apparent ipsilateral breast cancer recurrence. The majority of tumors were invasive. In the second study, the authors noted that 5 of the 28 women (18%) with previously undetected DCIS died of breast cancer.
Evidence from a meta-analysis (Cancer 1999;85:616-28) suggests that the risk for invasive recurrence following a mastectomy for DCIS is 1.1%, and that the risk for breast cancer death is less than 1.1%.
The risk for distant recurrence and/or death from breast-conserving surgery with or without adjuvant radiotherapy in prospective randomized trials of radiotherapy for DCIS was less than 5%. Among patients with invasive local failure in those trials, however, 18%-25% developed metastatic disease, indicating the importance of avoiding local recurrence.
Mastectomy and breast-conserving surgery combined with radiotherapy and/or endocrine therapy all provide excellent disease-specific and overall survival results, Dr. Van Zee said.
"The goal should be avoiding local recurrence and, in particular, invasive recurrence, minimizing morbidity, and perhaps individualizing the treatment to the disease. One could consider age, comorbidities, [and] life expectancy, and weigh those against the morbidity of the treatment and the risk of local recurrence," she said.
Dr. Van Zee reported no relevant financial disclosures.