Lung cancer age

Study objectives: Some investigators have suggested that lung cancer in young patients has a more aggressive course and a poorer prognosis than lung cancer in older patients. The aim of this study was to determine if the basal characteristics and survival in younger patients with lung cancer undergoing surgical resection differ from those of older patients.

Design: Retrospective clinical study.

Patients: Of 1,208 consecutive patients who underwent surgery for primary lung cancer between June 1984 and March 2000, we reviewed the medical records of 110 younger patients who were [is less than] 50 years of age at the time of surgery and compared them with 1,098 older patients ([is greater than or equal to] 50 years of age). All deaths were included.

Results: In the younger patient group, asymptomatic disease and adenocarcinoma was significantly more frequent, the rate of smoking was significantly higher, and the amount of smoking (Brinkman index) was significantly larger. For the 94 younger patients with complete resection, the 5-year survival rate was 61.0%, which was not significantly higher than that for the 923 older patients (57.7%). However, the 53 younger patients with stage I disease (5-year survival of 84.3%) had significantly better survival than older patients with the same condition (71.6%). Survival of patients in stage II or stage III disease was not significantly different.

Conclusion: The younger patients had significantly better prognoses, and a statistical difference was shown especially in the early stage, while in the advanced stage the malignancy of the lung cancer itself surpassed the difference in survival. (CHEST 2001; 120:32-36)

Key words: age; lung cancer; non-small cell lung cancer; surgery; young

Abbreviation: CEA = carcinoembryonic antigen; NS = not significant

Lung cancer is the leading cause of cancer-related mortality in both men and women. Although most cases of lung cancer occur in the sixth through eighth decades of life, 5 to 10% are diagnosed in patients [is less than] 50 years of age.[1]

There are characteristic features in young patients with lung cancer that differ from those in older patients with lung cancer: a relatively high incidence of female patients and a high incidence of adenocarcinoma.[2-4] An impression is widely held that young patients with lung cancer have a poorer prognosis than older patients. Many reports[2-9] have described survival rates in lung cancer patients with respect to age. Various investigators have concluded inferior[2,5,6,8] or equivalent[4,9] survival for younger compared to older patients, but the results are controversial and confusing. The purpose of this study was to analyze various clinical characteristics and long-term survival in younger patients ([is less than] 50 years of age) treated surgically for lung cancer compared with the older patients during the same period.

MATERIALS AND METHODS

Between June 1984 and March 2000, 1,412 consecutive patients with non-small cell lung cancer underwent pulmonary resection at our institution, of whom 204 patients with induction therapy were excluded from this analysis. Of these 1,208 patients, 110 patients (9.1%) [is less than] 50 years of age at the time of surgery were studied. Histopathologic diagnosis and staging were carried out according to the new TNM staging system,[10] revised in 1997. In 1,017 patients (94 younger and 923 older patients) with complete resections, lobectomy was by far the most common procedure and was performed in 763 patients (75.0%), including 104 combined sleeve resections of the bronchus. Thirty pneumonectomies (2.9%), including 3 sleeve resections, 176 segmentectomies (17.3%), 45 wedge resections, and 3 bronchial resections, were performed.

In this study, we excluded patients with malignant effusion detected before the operation. Immediately after thoracotomy, the pleural cavity was washed with 20 mL of normal saline solution, and a cytologic examination of the fluid was done. When the report result from the pathologist was positive, we diagnosed the disease as malignant effusion (T4)[11,12] and changed the complete resection into a simpler procedure.

Hilar and mediastinal lymph node dissections were routinely performed in patients with complete resection. The Brinkman index data[13] (the sum of the number of cigarettes smoked per day multiplied by years of smoking) were recorded for 775 patients (73 younger and 702 older patients; 64.2% of all cases), and there were no differences in missing data between younger and older patients. Carcinoembryonic antigen (CEA) was measured before and 1 month after surgery. The cut-off level for CEA was 5.0 ng/mL.

Data are expressed as the mean [+ or -] SE. The [chi square] test was used to compare differences between proportions. The Student's t test was used for analysis of continuous data. This study was a retrospective analysis, and follow-up data were obtained for all patients. Operative mortality rates imply 30-day postoperative mortality plus intraoperative mortality. Hospital death was defined as all deaths during initial hospital stay. The survival rates were estimated using the Kaplan-Meier method in 94 younger patients and 923 older patients who had complete resection. The log-rank test was used to compare survival rates. A p value [is less than] 0.05 was considered significant. Deaths included those due to cancer, noncancer, and unknown causes.

RESULTS

Of 1,208 lung cancer patients, 110 patients (9.2%) were [is less than] 50 years of age at the time of surgery. Within this group of younger patients, 97 patients (88.2%) were 40 to 49 years of age and only 13 patients (11.8%) were [is less than] 40 years of age.

Overall follow-up duration ranged from 5 to 171 months, with a mean of 41 months. The operative mortality rate was 0.33% (4 of 1,208 patients). These four patients died of hemorrhage, pulmonary infarction, acute myocardial infarction, and brain metastasis, respectively. Hospital deaths accounted for 1.1% (13 of 1,208 patients): interstitial pneumonia (n = 3), pulmonary fibrosis (n = 3), pneumonia (n = 2), acute myocardial infarction (n = 2), respiratory failure (n = 1), pulmonary infarction (n = 1), and brain metastasis (n = 1) after surgery during the same hospitalization period.

The difference in the male-to-female ratio was not significant (NS) between younger and older patients. In the younger patient group, asymptomatic disease and adenocarcinoma was diagnosed significantly more frequently, while squamous cell carcinoma was diagnosed significantly less. The number of smokers was significantly higher and the amount of smoking (Brinkman Index) was significantly larger in younger patients (Fig 1 and Table 1). However, there was no significant difference in the frequency of adenocarcinoma histologic subtypes (Table 2).

[ILLUSTRATION OMITTED]