TORAKOCHIRURGIA
DNA ploidy as an independent prognostic factor: 10-year results in a group of patients surgically treated for squamous cell lung cancer

Background: The biological variability of lung cancer is one of the causes of the unpredictable clinical outcome of the disease. Many investigators have devoted a lot of effort to finding molecular and biochemical prognostic factors that may prove helpful in the qualification of patients for postoperative chemotherapy. Notwithstanding various previous studies attempted to associate DNA quantification in cancer cells with the prognosis for lung cancer, there is a divergence of opinion about its value. The aim of the present study was to assess the impact of aneuploidy on late (10-year) survival in a group of patients treated surgically for squamous cell lung cancer.

Material and methods: We analyzed a group of 110 patients surgically treated for squamous cell lung cancer between 1995 and 1997. The group consisted of 95 men and 15 women, aged between 34 and 77 years (the average age being 60). We performed lobectomy in 52 cases, pneumonectomy in 47 cases, and other resections in 11 patients. Most of the patients were in IB (35 cases), IIB (26 patients) and IIIA (22 cases) pathological stage of the disease. Paraffin-embedded pathological samples underwent a cytometric analysis to determine the DNA content in cancer cells. The DNA index was established in each specimen. A statistical analysis was performed using Statistica 10.0 and StatXact 8 software.

Results: DNA aneuploidy was found in 44.5% of cases. We did not find any relationship between ploidy and age, gender, TNM stage, T stage, N stage or grading. The percentage of surgical procedures and adjuvant therapies in patients with aneuploid and diploid tumors was similar. Overall survival rates at 3, 5 and 10 years were 46.5%, 30.2%, and 30.2% for diploid patients and 25%, 22.2%, and 13.9% for patients with aneuploid tumors, respectively. Significant differences dependent on ploidy were observed in 3- and 10-year survival rates. More patients with aneuploid cancers died from distant metastases (78% of deaths), whereas local cancer recurrence was more frequent in patients with diploid tumors (32% of deaths). Multivariate analysis revealed TNM stage, T stage and DNA ploidy as independent factors affecting survival.

Conclusions: Aneuploidy appears to be a significant independent prognostic factor in patients with squamous cell lung cancer and can be useful in the qualification of patients for adjuvant therapy after surgery.