Second primary cancers in patients with laryngeal cancer: a population-based study.
BACKGROUND
Literature regarding incidence of site-specific second cancers after laryngeal cancer is limited. Risk factors associated with second primaries are unknown.


METHODS
Second primaries after laryngeal cancer in the SEER database (1973-1996) were analyzed for incidence, relative risk compared with the general population, and potential risk factors, including radiotherapy. Information on chemotherapy and tobacco smoking was not available in the SEER database.


RESULTS
Of 20,074 laryngeal cancer patients surviving at least 3 months, 3533 (17.6%) developed second cancers. The cumulative risk of developing a second cancer was 26% at 10 years and 47% at 20 years. Compared with age-adjusted, gender, and tumor-specific rates in the general population, laryngeal cancer patients had higher risks of second cancers overall (observed-to-expected ratio [O/E] = 1.68, 95% confidence interval [CI] = 1.58-1.79), head-and-neck (4.81 [4.31-5.58]), esophageal (3.99 [3.29-4.83]), and lung (3.56 [3.34-3.79]) cancer. Advanced age at initial diagnosis was associated with increased risks of second cancers (p = 0.0001). Radiotherapy was associated with increased risk of second cancers overall (relative risk [RR] = 1.10 [1.02-1.18], p = 0.012), especially second cancers of the lung (RR = 1.18, [1.05-1.33], p = 0.006) and possibly second cancers of the head and neck (RR = 1.26, [0.99-1.60], p = 0.061). Radiotherapy was associated with a 68% excess risk (RR = 1.68, [1.16-2.43], p = 0.007) of developing a second head-and-neck cancer in patients who survived more than 5 years. Second primary was associated with a poor survival (p = 0.0001).


CONCLUSIONS
Second cancers after laryngeal cancer are common, especially for long-term survivors. Radiotherapy was associated with a small increased risk of developing second cancers overall and long-term risk of head-and-neck cancers. This data should be interpreted with caution in light of the lack of information on chemotherapy and tobacco smoking in the SEER database. Prevention and early detection are indicated.
Gao
Xiang
X
Central Arkansas Radiation Therapy Institute, Little Rock, AR 72215, USA. xgaomd@yahoo.com
Fisher
Susan G
SG
Mohideen
Najeeb
N
Emami
Bahman
B
D000704:Analysis of Variance; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology* / Q000401:mortality / Q000532:radiotherapy; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D007822:Laryngeal Neoplasms / Q000453:epidemiology* / Q000401:mortality / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012306:Risk; D015996:Survival Rate; D017741:Survivors