Tobacco smoking and the risk of subsequent primary cancer among cancer survivors: a retrospective cohort study.

BACKGROUND: Smoking is a well-known risk factor for cancer; however, there is little evidence as to whether the smoking status of cancer survivors has any risk for subsequent primary cancer (SPC) incidence, regardless of the first cancer sites. PATIENTS AND METHODS: In total, 29,795 eligible patients with a first cancer between 1985 and 2004 were examined for SPC until the end of 2006, using a record linkage between hospital-based and population-based cancer registries. The association between smoking at the time of the first cancer diagnosis and three SPC groups (i.e. specific SPC, smoking-related SPCs, and all SPCs) was calculated by Poisson regression. RESULTS: Ever smokers had 59% and 102% higher risk for all SPCs and smoking-related SPCs, respectively, than never smokers. Cancer survivors who had recently stopped smoking had 18% and 26% less risk, respectively, for these SPCs than those who smoked at the diagnosis. We also found that, compared with those who had never smoked, cancer survivors who had ever smoked had a significantly elevated risk of oral/pharyngeal, esophageal, stomach, lung, and hematological SPCs, regardless of the first cancer sites. CONCLUSIONS: These findings indicate that smoking increases not only the first cancer but also a second or SPC. Moreover, the results from recent quitters versus current smokers suggest that smoking cessation may decrease the risk for SPC, especially for smoking-related SPCs in cancer survivors. Preventive measures are necessary to reduce not only SPC incidence but also tobacco use.

Risk factors for intrahepatic cholangiocarcinoma: a possible role of hepatitis B virus.

There are several established risk factors for intrahepatic cholangiocarcinoma (ICC), namely primary sclerosing cholangitis, fibropolycystic liver disease, parasitic infection, intrahepatic biliary stones and chemical carcinogen exposure. However, the majority of patients with ICC do not have any of these risk factors. Therefore, identification of other risk factors is warranted for the prevention and early detection of ICC. We evaluated the risk factors for ICC in a large-scale cohort study in the province of Osaka, Japan. This retrospective cohort study included 154,814 apparently healthy individual blood donors, aged 40-64 years at the time of blood donation in the period 1991-1993. The average observation period was 7.6 years, resulting in 1.25 million person-years of observation. Incident ICC cases were identified by linking the blood-donor database to the records in the population-based cancer registry for the province. There were 11 incident ICC cases during follow-up, with an incidence rate of 0.88 per 100,000 person-years. Compared with subjects aged 40-49 years, the subjects aged 50-54 years and 55-59 years had a significantly higher risk for ICC (hazard ratio [HR] = 5.90; 95%CI:1.08-32.31 and 11.07; 95%CI:1.98-61.79, respectively). Compared with those with ALT level of 19 Karmen Units (KU) or less, subjects with ALT level of 40 KU or higher had a significantly higher risk for ICC (HR: 8.30; 95%CI:1.47-46.83). Compared with those who tested negative for both HBsAg and anti-HCV, those who tested HBsAg-positive had a significantly higher risk for ICC (HR: 8.56; 95%CI: 1.33-55.20). Our results suggest that HBV infection and liver inflammation are independently associated with ICC development. These findings need to be verified by further large cohort studies.

Natural killer activity and its changes among participants in a smoking cessation intervention program--a prospective pilot study of 6 months' duration.

We examined the effect of smoking cessation on natural killer (NK) activity of peripheral blood lymphocytes in terms of a prospective study of 27 Japanese subjects who participated in a smoking cessation intervention program. This program was delivered by means of group-counseling offering 7 sessions of about 2 hours over 6 months to help smokers to discontinue the habit. Thirteen subjects ceased smoking (quitters), while 14 continued to smoke (cigarette smokers). NK activity before the intervention was correlated positively with age (correlation coefficient=0.46, P<0.05). NK activity remained almost constant among quitters, comparing the activity before and after the intervention, while it decreased among cigarette smokers although it was not statistically significant. In the subgroup analysis, NK activity increased among those aged less than 65 years, or urine cotinine levels over 800 ng/ml before the intervention, especially among quitters, but there were no statistical significances. Multiple regression analysis showed changes in NK activity were correlated significantly only with age (standard regression coefficient=-0.44, P<0.05). These findings suggest that smoking cessation intervention programs might have been more effective for younger than elder subjects in consideration of NK activity.