Breast cancer in young women: Pathologic features and molecular phenotype.

Purpose: Controversy exists about the prognosis of breast cancer in young women. Our objective was to describe clinicopathological and prognostic features to improve adjuvant treatment indications.

Methods: We conducted a retrospective multi centre study including fifteen French hospitals. Disease-free survival's data, clinical and pathological criteria were collected.

Results: 5815 patients were included, 15.6% of them where between 35 and 40 years old and 8.7% below 35. In 94% of the cases, a palpable masse was found in patients ≤35 years old. Triple negative and HER2 tumors were predominantly found in patients ≤35 (22.2% and 22.1%, p < 0.01). A young age ≤40 years (p < 0.001; hazard ratio [HR]: 2.05; 95% confidence limit [CL]: 1.60-2.63) or ≤35 years (p < 0.001; [HR]: 3.86; 95% [CL]: 2.69-5.53) impacted on the indication of chemotherapy. Age ≤35 (p < 0.001; [HR]: 2.01; 95% [CL]: 1.36-2.95) was a significantly negative factor on disease-free survival. Chemotherapy (p < 0.006; [HR]: 0.6; 95% [CL]: 0.40-0.86) and positive hormone receptor status (p < 0.001; [HR]: 0.6; 95% [CL]: 0.54-0.79) appeared to be protector factors. Patients under 36, had a significantly higher rate of local recurrence and distant metastasis compared to patients >35-40 (21.5 vs. 15.4% and 21.8 vs. 12.6%, p < 0.01).

Conclusion: Young women present a different distribution of molecular phenotypes with more luminal B and triple negative tumors with a higher grade and more lymph node involvement. A young age, must be taken as a pejorative prognostic factor and must play a part in indication of adjuvant therapy.