Second primary tumors involving non-small cell lung cancer: prevalence and its influence on survival

Patients with lung cancer have a relative high risk for second primary cancers. We studied the prevalence of second primary tumors in patients with a diagnosis of non-small cell lung cancer (NSCLC) in their history or at follow-up. Furthermore, we studied survival in subgroups of those patients.

Retrospectively, 860 patients with NSCLC that had been diagnosed in the period from January 1, 1990, to December 31, 1999, were evaluated for second primary cancers either in their history or in the follow-up period. The patients were divided into the following four groups: group I, patients with another primary tumor detected in the follow-up period (n = 44); group II, patients with another primary tumor in their history (n = 148); group III, patients with no other primary tumor found in their history or at follow-up (n = 634); and group IV, patients with more than one other primary tumor in found in their history or at follow-up (n = 34).

The most frequently diagnosed double tumors were located in the lungs, the head and neck region, and the urinary tract. The interval between another malignancy as the first tumor (group II, 83 months) and NSCLC as the second malignancy was significantly longer than vice versa (group I, 14.5 months; p < 0.05). In > 80% of patients, the second primary tumors were diagnosed within 1 year after NSCLC was diagnosed. The 5-year survival rate is significantly better for patients with more than two primary malignancies compared to patients without two primary malignancies and patients with one other tumor in their history (p = 0.004 and 0.012, respectively). The 5-year survival rate in patients with a second tumor in the follow-up period was better than in patients without any other second tumor (p = 0.029). As the TNM stage and therapy were comparable in all subgroups, it could not be used as explanation for the difference in survival rates.

In 25% of patients, additional tumors that were NSCLC were diagnosed either in their history or in the follow-up period. The majority of second tumors following NSCLC are diagnosed within 1 year. Nevertheless, patients with a second tumor tend to have an overall better survival rate than patients without second primaries, suggesting different growth habits.