Background: Clinical and histopathologic characteristics that may predict risks of recurrence in women with ductal carcinoma in situ (DCIS) have not been consistently identified. We identified factors associated with recurrence as DCIS versus invasive breast cancer and determined the 5-year absolute risks of recurrence as a function of these factors.
Methods: We conducted a population-based cohort study among 1036 women in the San Francisco Bay Area who were aged 40 years or older when diagnosed with DCIS and treated by lumpectomy alone from January 1983 through December 1994. Standardized pathology reviews were conducted to determine disease recurrence, defined as DCIS or invasive breast cancer diagnosed in the ipsilateral breast containing the initial DCIS lesion or at a distant site more than 6 months after the initial diagnosis and treatment of DCIS. Conditional logistic regression models were used to determine factors associated with recurrence. All statistical significance tests were two-sided.
Results: During a median follow-up of 77.9 months, 209 women (20.2%) experienced a recurrence. Overall, the 5-year risks of recurrence as invasive cancer and as DCIS were 8.2% (95% confidence interval [CI] = 6.6% to 9.8%) and 11.7% (95% CI = 9.9% to 13.3%), respectively. The 5-year risks of recurrence as invasive cancer and as DCIS were 4.8% (95% CI = 3.7% to 6.8%) and 4.8% (95% CI = 3.8% to 5.8%), respectively, for women with low-nuclear-grade DCIS; 11.8% (95% CI = 9.9% to 14.1%) and 17.1% (95% CI = 15.5% to 18.7%), respectively, for women with high-nuclear-grade DCIS; 11.6% (95% CI = 11.3% to 12.0%) and 8.6% (95% CI = 7.1% to 10.2%), respectively, for women whose initial DCIS lesion was detected by palpation; and 6.6% (95% CI = 6.2% to 7.1%) and 14.1% (95% CI = 11.4% to 17.8%), respectively, for women with DCIS detected by mammography alone. High- (versus low-) nuclear-grade DCIS lesions and detection of the initial DCIS lesion by palpation (versus mammography) were associated with recurrence as invasive cancer. High- (versus low-) nuclear-grade lesions; resection margins that were positive, uncertain, or less than 10 mm disease-free (versus > or = 10 mm disease-free); and age 40-49 years at diagnosis (versus > or =50 years) were associated with recurrence as DCIS.
Conclusions: Nuclear grade is strongly associated with recurrence but not with the type of recurrence. Women with high-nuclear-grade DCIS or DCIS detected by palpation who are treated by lumpectomy alone are at relatively high risk of having an invasive breast cancer recurrence, compared with women with low-nuclear-grade or mammographically detected DCIS, and may be appropriate candidates for additional treatment.