Incidence and patterns of second primary malignancies following oral cavity cancers in a prevalent area of betel-nut chewing: a population-based cohort of 26,166 patients in Taiwan.
OBJECTIVE
The incidence of oral cavity cancers is increasing rapidly in South-East Asia, which may be attributable to tobacco smoking, alcohol and betel-nut chewing. However, the actual incidence and risk of second primary malignancies after oral cavity cancers have not been well established in this region. A population-based study was therefore conducted.


METHODS
Standardized incidence ratios and cumulative incidences were calculated for second primary cancers using the Taiwan Cancer Registry database for the period 1979-2003, which included 26 166 cases having an initial diagnosis of oral cavity cancers.


RESULTS
A 3.11-fold increase in risk for second cancer at all sites was observed after oral cavity cancers compared with the general population (standardized incidence ratio = 3.11, 95% confidence interval: 2.97-3.25). Of nine sites with excess risks of developing a second cancer, the frequency was highest in the oral/pharynx (60%), followed by lung (7.2%) and esophagus (5.5%). Second esophageal and lung cancers had a greater impact on survival compared with other types of second cancer. Notably, the risk excess was more prominent for patients with a follow-up interval of ≤ 1 year and a first primary cancer diagnosed at age of ≤ 40. These patients may justify closer surveillance.


CONCLUSIONS
This is the largest population-based study with a homogeneous patient population focusing on oral cavity cancers within a high-incidence area. We found that oral cavity cancers are associated with an increased risk of nine second malignancies, which had a negative impact on survival.
Department of Hematology and Oncology, Chang Gung Memorial Hospital at Chiayi, Pu-Tz city, Taiwan.
Ping-Tsung
PT
Chen
Feng-Che
FC
Kuan
Cih-En
CE
Huang
Miao-Fen
MF
Chen
Shih-How
SH
Huang
Min-Chi
MC
Chen
Kuan-Der
KD
Lee
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001114:Areca / Q000009:adverse effects*; D044466:Asian People / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000208:ethnology* / Q000209:etiology / Q000401:mortality; D016609:Neoplasms, Second Primary / Q000208:ethnology* / Q000209:etiology / Q000401:mortality; D016016:Proportional Hazards Models; D012306:Risk; D015996:Survival Rate; D013624:Taiwan / Q000453:epidemiology