Asian Cardiovasc Thorac Ann 2008;16:387-391
© 2008 Asia Publishing EXchange Ltd
Clinical Characteristics and Surgery of Primary Lung Cancer in Younger Patients
Yasunobu Funakoshi, MD,
Shin-ichi Takeda, MD,
Yoshihisa Kadota, MD,
Takashi Kusu, MD,
Hajime Maeda, MD
Department of General Thoracic Surgery, Toneyama National Hospital, Osaka, Japan
For reprint information contact: Yasunobu Funakoshi, MD Tel: 81 6 6853 2001 Fax: 81 6 6850 1750 Email: funakosy{at}toneyama.go.jp, Department of General Thoracic Surgery, Toneyama National Hospital, 5-5-1 Toneyama, Toyonaka, Osaka, 560-8552, Japan.
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ABSTRACT
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Controversy exists regarding the clinical characteristics, pathological findings, and prognosis of patients < 50 years of age with primary lung cancer. The medical records of 4,556 patients diagnosed with primary lung cancer between 1980 and 2004 were reviewed; of these, 305 were < 50 years old. Of 1,335 patients who were surgically treated, 122 were < 50 years old. Females were over-represented in the younger group. Younger patients had a significantly higher incidence of adenocarcinoma and large cell carcinoma, and a lower incidence of squamous cell carcinoma. The resectable rate in younger patients was significantly higher. Overall and among surgically treated patients, the survival rates of younger patients with stage 0-I disease were significantly better than those of older patients. Younger patients with early-stage primary lung cancer had a significantly better prognosis than older patients, although survival in the advanced stages was not significantly different.
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INTRODUCTION
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Lung cancer is the leading cause of cancer-related mortality in the United States as well as Japan. Lung cancer occurs most frequently in the 6th to 8th decades of life and is relatively rare in younger patients.1 Only 5% 12.5% of lung cancers are diagnosed in patients < 50 years old.2–5 Clinical characteristics and pathological findings in younger patients with lung cancer differ from those in older patients, exhibiting a higher proportion of females and a higher incidence of adenocarcinoma.5–11 Several retrospective studies have suggested that younger patients have a worse prognosis than older patients, whereas others have reported that the prognoses of both groups are similar.3,6–15 In addition, many studies have been limited by small sample size, and several previous reports have considered only patients who underwent surgery.4,6,9 To overcome these limitations, we analyzed the data of all 4,556 patients who were diagnosed with primary lung cancer, including a cohort of 1,335 who underwent surgery during the study period. This study was performed to characterize the clinical and pathological features of lung cancer in patients < 50 years of age, and to compare survival rates in younger and older patients.
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PATIENTS AND METHODS
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This retrospective analysis was based on the database of patients with primary lung cancer who had been histologically diagnosed at Toneyama National Hospital. Between 1980 and 2004, 4,814 patients were newly diagnosed with primary lung cancer. Of these, 4,556 patients were analyzed in this study; 39 whose records were incomplete and 219 who were lost to follow-up were excluded. There were 305 (6.7%) patients < 50 years old when diagnosed. Over the study period, 1,335 (29.3%) patients underwent surgery, of whom 122 were < 50 years old and 1,213 were 
50 years old. All patients underwent staging according to the 1997 TNM classification criteria.16 Those who had undergone resection before 1997 had their disease reclassified according to this TNM system. Patients with carcinoid tumor, adenoid cystic carcinoma, mucoepidermoid carcinoma, and sarcoma were excluded from this study.
Operative mortality was defined as all deaths during the initial hospital stay. Respiratory complications included atelectasis, sputum retention requiring bronchoscopy, pneumonia, bronchial asthma, air leak requiring tube drainage for more than 7 days, and empyema. Cardiac complications included arrhythmia, myocardial infarction, and acute heart failure. Other complications were liver or renal dysfunction. Comorbidities comprised previous history of pulmonary, cardiovascular diseases and cerebral infarction, renal dysfunction, severe liver disease, diabetes mellitus, and gastric ulcer.
The chi-squared test was used to compare differences between groups. Survival was defined as the time between diagnosis and death. The survival rates were calculated using the Kaplan-Meier method and compared using the log-rank test. A p value < 0.05 was considered statistically significant.
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RESULTS
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The median follow-up duration was 133 months. The characteristics of all 4,556 patients with primary lung cancer are given in Table 1
. There was a significant difference in male-to-female ratios between the younger and older groups. Although adenocarcinoma was the most common histologic subtype according to this TNM in both groups, the distribution of histologic subtypes in the younger patients was significantly different from that in older patients. Comorbidity data were available for 163 younger patients and 2,739 older patients who were treated after 1992. The incidence of comorbidity was significantly less in the younger patients (25% vs 46%; p < 0.0001). Younger patients were more likely to undergo surgery, but there were no differences in sex, clinical stage, or pathologic stage between the 2 age groups (Tables 2 and 3). The distribution of histologic subtypes (Table 2) in surgically treated patients showed more adenocarcinoma and less squamous cell carcinoma in the younger group. There was no significant difference in the occurrence of bronchioloalveolar carcinoma between groups (2.5% vs 4.0%; p = 0.48). Surgical procedures were similar in both groups (Table 3). The operative mortality rate was 0% in the younger group and 0.9% in the older group. Postoperative complications occurred in 10 (8.2%) younger patients and 179 (14.8%) older patients (p = 0.048). The overall survival curves for both age groups according to clinical stage are shown in Figure 1A. Younger patients with clinical stage 0 I disease had significantly better survival than older patients. Survival after surgical resection, according to pathologic stage, is shown in Figure 1B. Younger patients with pathologic stage 0 I disease had marginally better survival than older patients. The prognosis of patients with pathologic stage II IV disease was equally poor in both groups.
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DISCUSSION
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This study found significant differences in sex ratio, histologic subtypes, and resectable rate of lung cancer in patients older or younger than 50 years at the time of diagnosis. Younger patients with early-stage lung cancer were noted to have significantly better survival rates than older patients. One difficultyin comparing the results of prior reports on young lung cancer patients is the variability of the age cutoff used to define "young". In this study, 50 years of age was selected to ensure adequate numbers of younger patients for meaningful statistical analyses, and because the incidence of lung cancer increases rapidly beyond this age.2–5 The much lower male-to-female ratio in younger patients supports the findings of previous studies.5–11,15
In the past decade, adenocarcinoma has surpassed squamous cell carcinoma as the most common histologic subtype of lung cancer.3,17 Compared with older patients, adenocarcinoma was diagnosed significantly more frequently in younger patients, while squamous cell carcinoma was less common. The distribution of histologic subtypes between the age groups was significantly different, as found previously.3–13 Squamous cell carcinoma requires a longer exposure to carcinogens, which may account for the different distribution.8
Many reports have suggested that younger patients present more frequently in advanced stages of lung cancer, perhaps due to delayed diagnosis resulting from a low degree of suspicion of cancer in these patients.3,7–9,12–15 In this study, however, the distribution of clinical and pathologic stages was similar in both age groups of patients undergoing surgery. As reported by others, there was a significant difference in resectability.3,5 Furthermore, there were fewer comorbidities in the younger group. We suggest that the higher degree of resectability in younger patients may be related to their lower rate of comorbidity. Of the 122 younger patients who were surgically treated, 8 underwent bronchoplasty, 11 had combined resections, and 16 had a pneumonectomy, including 12 who had multi-modality therapy. This indicates that younger patients are more likely to be treated aggressively, probably because of their perceived better physical condition.3,5,14
Differences in the survival rates of younger and older patients are important to consider in clinical practice. Several studies have documented lower overall survival rates in younger patients, whereas others have reported similar rates between age groups.3,6–10,12–15 Although we found no difference in the survival rates of clinical and pathologic stages II IV between groups, younger patients with early-stage disease had a significantly better prognosis. Minami and colleagues4 also reported that younger patients with stage I disease had significantly better survival than older patients. In the advanced stages of disease, the survival rate of younger patients is not better than that of older patients, despite the high incidence of resectability. Operative mortality and morbidity tended to be lower in the younger group, suggesting that if lung cancer could be detected and treated surgically in the early stages, younger patients would achieve much better survival than older patients, most likely due to their better overall health, performance status, and the absence of comorbidities.5 In contrast, younger patients in advanced stages have as poor a prognosis as older patients, despite receiving more aggressive therapy.
In this study, the rates of complete resection of younger and older patients were 84% and 87%, respectively. Together, these data appear to suggest that lung cancer is more aggressive in younger patients, highlighting the importance of close monitoring of younger patients for early signs of the disease. Even in cases where there is a low degree of suspicion of cancer, efforts to detect lung cancer in the early stages are warranted to initiate treatment early in younger patients.
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REFERENCES
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- Jemal A, Murray T, Ward E, Samuels A, Tiwari RC, Ghafoor A, et al. Cancer statistics, 2005. CA Cancer J Clin 2005;55:10–30.[Abstract/Free Full Text]
- Schottenfeld D. Epidemiology of lung cancer. In: Pass HI, Mitchell JB, Johnson DH, Turrisi AT, editors. Lung cancer: principles and practice. Philadelphia: Lippincott-Raven, 1996:305–21.
- Gadgeel SM, Ramalingam S, Cummings G, Kraut MJ, Wozniak AJ, Gaspar LE, et al. Lung cancer in patients <50 years of age: the experience of an academic multidisciplinary program. Chest 1999;115:1232–6.[Medline]
- Minami H, Yoshimura M, Matsuoka H, Toshihiko S, Tsubota N. Lung cancer treated surgically in patients <50 years of age. Chest 2001;120:32–6.[Medline]
- Ramalingam S, Pawlish K, Gadgeel S, Demers R, Kalemkerian GP. Lung cancer in young patients: analysis of a surveillance, epidemiology, and end results database. J Clin Oncol 1998;16: 651–7.[Abstract]
- Shimono T, Hayashi T, Kimura M, Yada I, Namikawa S, Yuasa H, et al. Surgical treatment of primary lung cancer in patients less than 40 years of age. J Clin Oncol 1994;12:981–5.[Abstract/Free Full Text]
- Jubelirer SJ, Wilson RA. Lung cancer in patients younger than 40 years of age. Cancer 1991;67:1436–8.[Medline]
- Antkowiak JG, Regal A, Takita H. Bronchogenic carcinoma in patients under age 40. Ann Thorac Surg 1989;47:391–3.[Abstract]
- Sugio K, Ishida T, Kaneko S, Yokoyama H, Sugimachi K. Surgically resected lung cancer in young adults. Ann Thorac Surg 1992;53: 127–31.[Abstract]
- DeCaro L, Benfield JR. Lung cancer in young persons. J Thorac Cardiovasc Surg 1982;83:372–6.[Abstract]
- Green LS, Fortoul TI, Ponciano G, Robles C, Rivero O. Bronchogenic cancer in patients under 40 years old. The experience of a Latin American country. Chest 1993;104:1477–81.[Medline]
- Bourke W, Milstein D, Giura R, Donghi M, Luisetti M, Rubin AH, et al. Lung cancer in young adults. Chest 1992;102:1723–9.[Medline]
- Etzel CJ, Lu M, Merriman K, Liu M, Vaporciyan A, Spitz MR. An epidemiologic study of early onset lung cancer. Lung Cancer 2006;52:129–34.[Medline]
- Lienert T, Serke M, Schonfeld N, Loddenkemper R. Lung cancer in young females. Eur Respir J 2000;16:986–90.[Abstract]
- Liu NS, Spitz MR, Kemp BL, Cooksley C, Fossella FV, Lee JS, et al. Adenocarcinoma of the lung in young patients: the M. D. Anderson experience. Cancer 2000;88:1837–41.[Medline]
- Sobin LH, Wittekind CH, editors. International Union Against Cancer (UICC). TNM classification of malignant tumors.5 th ed. New York: Wiley, 1997.
- Goya T, Asamura H, Yoshimura H, Kato H, Shimokata K, Tsuchiya R, et al. Prognosis of 6644 resected non-small cell lung cancers in Japan: a Japanese lung cancer registry study. Lung Cancer 2005;50:227–34.[Medline]
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ABSTRACT
INTRODUCTION
