Background: Breast cancer survival is improving because mammography is leading to diagnosis at earlier stages of the disease. Because young women with breast cancer rarely undergo mammography before diagnosis, outcomes for breast cancer in young women may not be improving. In addition to advanced stage, young age at diagnosis is associated with biologically more aggressive cancers with higher rates of local and distant recurrence.
Study design: Risk factors, clinical presentations, pathologic findings, tumor characteristics, extent of disease, treatment, and outcomes for 101 women under age 36 treated for breast cancer between 1989 and 1997 were compared with 631 patients 36 years and older treated by us during the same interval. Stage IV patients were excluded.
Results: Patients younger than 36 years were more likely to present with a palpable mass (87% versus 55%, p < 0.001) and were less likely to undergo spot localization breast biopsy for mammographic findings (40% versus 6%, p < 0.001). Patients younger than 36 years had larger tumors (median 2.0 cm versus 1.5 cm, p < 0.001), more nodal involvement (50% versus 37%, p = 0.022), more nodes involved (median 1.0 versus 0, p = 0.010), and were more likely to be diagnosed with stage II or III cancer (60% versus 43%, overall p < 0.001). Young patients' cancers were more poorly differentiated (80% versus 44%, overall p < 0.001), estrogen receptor-negative (52% versus 31%, p < 0.001), aneuploid (70% versus 49%, p = 0.013), and had higher S-phase fractions (59% versus 29%, p = 0.001). Patients less than 36 years were treated more often with mastectomy (59% versus 22%, p < 0.001) and adjuvant chemotherapy (80% versus 54%, p < 0.001) and less often with tamoxifen (36% versus 58%, p = 0.001). Cumulative 5-year local and distant disease-free survival were significantly worse for patients younger than 36 years (p = 0.011 and p = 0.044, respectively). The higher rate of local recurrence in patients less than 36 years was from an excess number of local recurrences in patients treated with breast conservation. After consideration for nodal involvement, chemotherapy, and tamoxifen using the Cox proportional hazards model, no other variable, including age, was significantly related to local disease-free outcomes. After consideration for tumor size and nodal involvement, no other variable was significantly related to distant disease failure rates.
Conclusions: Patients diagnosed with breast cancer before age 36 differ from older patients in numerous respects. They present more often with a palpable mass rather than a mammographic finding and their cancers are more advanced with features that are more aggressive. Despite aggressive treatment, most commonly with mastectomy and chemotherapy, local and distant failure rates are higher than for patients 36 and older. The higher rate of local recurrence in patients less than 36 years reflects an excess number of local recurrences in patients treated with breast conservation.