Apoptosis and mitosis as prognostic factors in pathologically staged N1 nonsmall cell lung cancer

This study aimed to established whether spontaneous apoptosis or mitosis has prognostic value among patients with pathologically staged N1 nonsmall cell lung carcinoma (NSCLC) treated with surgical resection with or without adjuvant therapy.

Material from 173 patients who had resections between 1970 and 1988 was analyzed for apoptosis and mitosis. There were 128 men and 45 women, with a median age of 61 years. There were 86 squamous cell carcinomas (SQ), 73 adenocarcinomas (AC), 3 large-cell carcinomas (LC), 6 SQ-AC, and 5 unclassified. Patients were observed from 2 to 209 months (median 27). Actuarial methods were used to assess survival and freedom from distant metastasis.

In NSCLC, apoptosis was found to range from 0.2% to 2.8% (median 1.0%) and mitosis from 0 to 1.8% (median 0.4%). Tumors having higher levels of apoptosis also had higher levels of mitosis (p = 0.001). The values of neither apoptosis nor mitosis depended on size, location, differentiation of tumors, age, performance status, or weight loss of patients. However, the values of apoptosis depended on tumor histology in that high values (greater than or equal to the median) were more frequent in SQ (49%) than in AC/LC (29%) (p = 0.01). The overall survival for NSCLC patients, which was 33% at 5 years, did not depend on the level of either apoptosis or mitosis. The 5-year survival of patients having SQ was higher (43%) than that of patients having AC/LC (21%) (p = 0.03). Patients with high apoptosis showed significantly better 5-year overall (p = 0.008) and DMF (p = 0.0012) survivals in the SQ group compared to the AC/LC group. High mitosis compared to low mitosis was a significantly better predictor for 5-year survival (62% vs. 29%, respectively) (p = 0.035) in the SQ. However, high mitosis was a significantly worse 5-year DMF survival predictor compared to low mitosis: 13% vs. 56%, respectively (p = 0.05) in AC/LC. In the multivariate models for AC/LC, mitosis remained a significant predictor of 5-year distant metastasis (p = 0.025) controlling for treatment groups (p = 0.042), whereas apoptosis was an independently significant predictor of 5-year distant metastasis (p = 0.010).

Squamous cell histology predicted significantly better 5-year overall and DMF survivals compared to AC/LC. Apoptosis was correlated with mitosis. Although apoptosis or mitosis did not predict survival or DM, high apoptosis or mitosis predicted significantly better survival in SQ and significantly worse survival in AC/LC with regard to overall and DMF survivals. In the multivariate models for AC/LC, apoptosis alone or mitosis with variable treatment was a significant predictor of 5-year distant metastasis. Thus, pretreatment levels of apoptosis or mitosis might be useful for predicting treatment outcome of SQ and AC/LC subsets of NSCLC when analyzed separately and for predicting metastatic incidence of AC/LC.