Prognostic value of mitotic counts in axillary node negative breast cancer patients with predominantly well-differentiated tumours

Phosphohistone H3 expression has much stronger prognostic value than classical prognosticators in invasive lymph node-negative breast cancer patients less than 55 years of age

The proliferation factor mitotic activity index is the strongest prognostic factor in early breast cancer, but it may lack reproducibility. We analyzed the prognostic value of phosphohistone H3, a marker of cells in late G(2) and M phase, measuring highly standardized immunohistochemical nuclear phosphohistone H3 expression by subjective counts and digital image analysis. Expression was compared with classical clinico-pathologic prognostic variables and the mitotic activity index in 119 node-negative invasive breast cancers in patients less than 55 years old treated with adjuvant systemic chemotherapy with long-term follow-up (median 168 months). Nineteen patients (16%) developed distant metastases and 16 (13%) died. Strong phosphohistone H3 expression occurred preferentially in the peripheral growing front; counts were highly reproducible between observers (R=0.92) and highly consistent with digital image analysis (R=0.96). Phosphohistone H3 correlated (P<0.05) with tumor diameter, estrogen receptor, carcinoma grade, and mitotic activity index. Phosphohistone H3 values were systematically (80%) higher than the mitotic activity index. Receiver-operating curve analysis objectively showed that phosphohistone H3 <13 (n=53; 45% of all cases) vs phosphohistone H3> or =13 (n=66; 55% of all cases) was the strongest prognostic threshold, with 20-year recurrence-free survival of distant metastases of 96 and 58%, respectively (P=0.0002, HR=9.6). Mitotic activity index was the second strongest prognostic variable (P=0.003, HR=3.9). In multivariate analysis, phosphohistone H3 <13 vs> or =13 exceeded the prognostic value of the mitotic activity index. None of the other classical prognostic factors examined offered prognostic value additional to phosphohistone H3. Phosphohistone H3 is by far the strongest prognostic variable in early invasive node-negative breast cancer patients less than 55 years old with long-term follow-up.

The prognostic value of proliferation in lymph-node-negative breast cancer patients is age dependent

In lymph-node-negative invasive breast cancer patients<55 years, the proliferation marker mitotic activity index (MAI) has previously been shown to be the strongest prognosticator. In studies without age definition, MAI was not strongly prognostic. We investigated the age dependency of the prognostic value of proliferation for distant metastasis-free (MFS) and overall cancer-related survival (OS) in 1004 histologically diagnosed T1-3N0M0 invasive breast cancers (n=516, <55 years; n=322, 55-70 years; n=166, >70 years) without systemic adjuvant therapy and long follow-up (median: 108 months). The MAI decreases with age and the prognostic value of MAI varied by age group. For patients<55 years, hazard ratios (HR) for MAI>or=10 versus<10 for MFS and OS were 3.1 and 4.4, respectively (P<.0001 for both), but only 1.9 and 1.9 (P=.004 and .006) for patients aged 55-70 years, while over 70 years, MAI was not significant (P=.11). The prognostic value of proliferation was age-dependent. Prognostic breast cancer studies must clearly indicate the age group being studied.