Predictors of local recurrence after treatment of ductal carcinoma in situ- A meta-analysis

lBACKGROUND. Management of patients with ductal carcinoma in situ (DCIS) is a dilemma, as mastectomy provides nearly a 100% cure rate but at the expen se of physical and psychologic morbidity. It would be helpful if we could p redict which patients with DCIS are at sufficiently high risk of local recu rrence after conservative surgery (CS) alone to warrant postoperative radio therapy (RT) and which patients are at sufficient risk of local recurrence after CS + RT to warrant mastectomy. The authors reviewed the published stu dies and identified the factors that may be predictive of local recurrence after management by mastectomy, CS alone, or CS + RT. METHODS. The authors examined patient, tumor, and treatment factors as pote ntial predictors for local recurrence and estimated the risks of recurrence based on a review of published studies. They examined the effects of patie nt factors (age at diagnosis and family history), tumor factors (sub-type o f DCIS, grade, tumor size, necrosis, and margins), and treatment (mastectom y, CS alone, and CS + RT). The 95% confidence intervals (CI) of the recurre nce rates for each of the studies were calculated for subtype, grade, and n ecrosis, using the exact binomial; the summary recurrence rate and 95% CI f or each treatment category were calculated by quantitative meta-analysis us ing the fixed and random effects models applied to proportions. RESULTS, Meta-analysis yielded a summary recurrence rate of 22.5% (95% CI = 16.9-28.2) for studies employing CS alone, 8.9% (95% CI = 6.8-11.0) for CS + RT, and 1.4% (95% CI = 0.7-2.1) for studies involving mastectomy alone. These summary figures indicate a clear and statistically significant separa tion, and therefore outcome, between the recurrence rates of each treatment category, despite the likelihood that the patients who underwent CS alone were likely to have had smaller, possibly low grade lesions with clear marg ins. The patients with risk factors of presence of necrosis, high grade cyt ologic features, or comedo subtype were found to derive the greatest improv ement in local control with the addition of RT to CS. Local recurrence amon g patients treated by CS alone is approximately 20%, and one-half of the re currences are invasive cancers. For most patients, RT reduces the risk of r ecurrence after CS alone by at least 50%. The differences in local recurren ce between CS alone and CS + RT are most apparent for those patients with h igh grade tumors or DCIS with necrosis, or of the "comedo" subtype, or DCIS with close or positive surgical margins. CONCLUSIONS, The authors recommend that radiation be added to CS if patient s with DCIS who also have the risk factors for local recurrence choose brea st conservation over mastectomy. The patients who may be suitable for CS al one outside of a clinical trial may be those who have low grade lesions wit h little or no necrosis, and with clear surgical margins. Use of the summar y statistics when discussing outcomes with patients may help the patient ma ke treatment decisions. Cancer 1999;85:616-28. (C) 1999 American Cancer Soc iety.