Impact of detection method and accompanying ductal carcinoma in situ on prognosis of T1a, bN0 breast cancer

Background: T1a, bN0 breast cancer is not easily detected. Before mammography became widespread, most cases were discovered only after the development of symptoms. The presence of ductal carcinoma in situ (DCIS) affects the detectability of associated invasive cancer; however, the prognostic value of concomitant DCIS is controversial. This study compared the characteristics of screening-detected and symptom-detected T1a, bN0 breast cancer, and investigated the impact of accompanying DCIS on detection and prognosis. Patients and Methods: Data were collected from a single hospital between 2000 and 2009. Of 5,690 primary breast cancers patients, 438 met the criteria for T1a, bN0M0. Logistic regression models were used to identify prognostic indicators and their association with the detection method. Survival analyses were performed to estimate distant relapse-free survival (DRFS) and breast cancer-specific survival (BCSS). Results: Tumors in 79 and 359 patients were detected by screening and development of symptoms, respectively. Symptomatic cancer patients were younger, more likely to receive a mastectomy, and had larger accompanying DCIS lesions; their 10-year DRFS rates were worse than those of patients with screening-detected tumors (91.1% vs. 100% respectively, p=0.049). Patients with large accompanying DCIS (≥2 cm) had markedly worse 10-year DRFS (77.1% vs. 97.4%, p<0.001) and BCSS (94.3% vs. 98.9%, p<0.001). Conclusion: T1a, bN0 breast cancers detected owing to symptoms are more likely to have larger accompanying DCIS. T1a, bN0 patients with large accompanying DCIS have worse DRFS and BCSS. It is important to consider associated DCIS size when evaluating prognosis in T1a, bN0 breast cancer patients.