Truong-Minh Pham

Reproductive and menstrual factors and thyroid cancer among Japanese women: the Japan Collaborative Cohort Study.

AIM Thyroid cancer is more frequent in women than in men, suggesting the potential role of reproductive and menstrual factors in this cancer. To investigate the association with these factors, we examined 37,986 women involved in the Japan Collaborative Cohort (JACC) Study from 1988 to 1997. METHODS Reproductive and menstrual factors were assessed with a self-administered questionnaire at baseline. Hazard ratios (HR) and 95% confidence intervals (95% CI) of thyroid cancer incidence were estimated using Cox proportional hazards regression. RESULTS Eighty-six new cases of thyroid cancer were recorded during 379,281 person-years of follow-up. Overall incidence rate was 22.7 per 100,000 person-years, with a diagnosed peak of 38.2 per 100,000 at 55-59 years old. Multivariate HRs of 0.56 (95% CI 0.25-1.24) and 0.52 (95% CI 0.24-1.16) were observed for women who had experienced pregnancy or a live birth, respectively, but without statistical significance. Further, we saw no associations with other factors, such as age at menarche, age at menopause, age at first birth, or hormone use. CONCLUSIONS There was no significant association between thyroid cancer and reproductive and menstrual factors in the present study. Additional cohort studies should further examine this possible relationship among Japanese women.

Prospective study of vegetable consumption and liver cancer in Japan

We examined the relationship between vegetable consumption and the risk of death from liver cancer in a cohort study in Japan. This analysis is based on data from 6,049 subjects aged 40 to 79 years enrolled in a cohort study conducted in Fukuoka Prefecture, Japan. The follow‐up period was from 1986 to 1999. All liver cancer deaths were recorded. The vegetable consumption was classified into 3 groups: “once per week or less,” “2–4 times per week” and “daily intake.” The Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence interval (95% CI). A total of 51 male and 22 female liver cancer deaths were recorded during 62,343 person‐years of follow‐up. The “once per week or less” group was considered the referent group. In males, the multivariate HRs of liver cancer deaths were 0.61 (95% CI: 0.33–1.14) and 0.25 (95% CI: 0.11–0.59) in the “2–4 times per week” and “daily intake” groups, respectively. In females, the multivariate HRs were 0.44 (95% CI: 0.13–1.51) and 0.51 (95% CI: 0.16–1.69), respectively. The multivariate HRs were also reported by history of hepatitis and cirrhosis. In those without a history of these conditions, the multivariate HRs were 0.54 (95% CI: 0.27–1.09) and 0.36 (95% CI: 0.16–0.83). In those with a history of these conditions, the multivariate HRs were 0.58 (95% CI: 0.22–1.56) and 0.37 (95% CI: 0.13–1.06), respectively. Our study reveals an inverse association between vegetable consumption and the risk of death from liver cancer. These results provide further evidence of the protective effect of vegetables against liver cancer.

Years of life lost due to cancer in a cohort study in Japan.

BACKGROUND We estimated the burden of cancer using mortality and years of life lost according to life tables in a cohort study in Japan. METHODS A cohort of 13,270 subjects established in the late 1980s in Japan was followed annually for the vital status of all subjects until 2003. For subjects who died, the underlying cause of death was ascertained from the death certificate. Crude mortality rate from cancer per 100,000 person-years was calculated, and years of life lost (YLL) as well as the average years of life lost (AYLL) were computed using the 1995 life tables in Japan. RESULTS During the follow-up period, we recorded a total 839 cancer deaths (517 men and 322 women), representing 35.5% of deaths from all causes. Overall crude cancer mortality was 654.9 per 100 000 person-years in men and 312.6 in women. Total YLL due to cancer was 7035.3 years in men and 5627.0 years in women. Overall AYLL due to all cancers was 13.6 years less than life expectancy in men and 17.5 years in women. CONCLUSION These results showed that cancer was the leading cause of death in this cohort; with stomach, liver and lung cancer the three most frequent cancers in both sexes. YLL and AYLL reflect the cost of dying from cancer in terms of years of life expectancy lost. The different mortality statistics used here may be useful in public health considerations of cancer burden.

Premature mortality due to cancer in Japan, 1995 and 2005

To better understand premature mortality due to cancer, we estimated years of life lost (YLL) and average years of life lost (AYLL) due to cancer for the years 1995 and 2005, based on data from the Vital Statistic of Japan. In men, we identified a total of 159,623 cancer deaths in 1995 and 196,603 in 2005. Total YLL were 2,342,560.4 and 2,724,066.0 years, respectively. Averaged for all cancers, people died 14.7 years earlier than life expectancy in 1995 and 13.9 years in 2005. AYLL was longest for brain cancer deaths, at 26.3 years earlier than expected in 1995 and 22.8 years in 2005, followed by leukemia. In women, a total of 103,399 cancer deaths occurred in 1995 and 129,338 in 2005. Total YLL were 1,818,960.4 years in 1995 and 2,160,706.5 years in 2005, corresponding to AYLL for all cancer combined of 17.6 and 16.7 years. The AYLL of brain cancer deaths was also the longest, at 29.4 years in 1995 and 27.8 in 2005, followed by leukemia and female sex‐related cancers. Results showed that cancer of the stomach, colorectum, liver and lung were the most frequent cancers in both sexes in both 1995 and 2005 and responsible for a remarkable number of YLL. Further, AYLL was greatest for brain cancer and leukemia in both sexes and for sex‐related cancers in women, namely breast, cervix and ovarian cancer.

Reproductive factors in relation to ovarian cancer: a case–control study in Northern Vietnam

BACKGROUND Ovarian cancer, one of the most common cancers in women and the most serious gynecologic cancer, is known to be influenced by reproductive factors, but these factors have not previously been examined in Vietnamese women. STUDY DESIGN We analyzed 262 ovarian cancer patients recruited from 27 hospitals in 12 provinces and Ha Noi City from April 2001 to May 2006, plus 755 controls matched by age and residential address. RESULTS The risk of ovarian cancer was significantly lower in parous women than nulliparous women. Use of an intrauterine contraceptive device was also associated with a reduced risk. In contrast, induced abortion, late menopause and years of ovulation were significantly associated with an increased risk of cancer. CONCLUSIONS Parity and intrauterine device use were associated with a reduced risk of ovarian cancer in Vietnamese women, whereas induced abortion, late menopause and years of ovulation were associated with an increased risk.

Oral Symptoms Predict Mortality: a Prospective Study in Japan

Several studies have reported positive associations between oral infections and systemic diseases. The purpose of the present study was to evaluate the effects of oral symptoms on mortality from cardiovascular disease (CVD) and pneumonia. Using data from a cohort study in Japan, we analyzed 4,139 individuals aged 40–79 years. The baseline questionnaire included the following items related to oral symptoms: ‘sensitive teeth’, ‘difficulty in chewing tough food substances’, ‘bleeding gums’, and ‘mouth feels sticky’. We used the Cox proportional hazard model to estimate hazard ratios (HRs) and 95% confidence intervals (95%CIs) for mortality, after adjustments for lifestyle, socio-economic factors, and history of diseases. Persons complaining that their ‘mouth feels sticky’ had a two-fold higher risk of pneumonia (HR = 2.1; 95%CI, 1.2–3.6), while those complaining of ‘sensitive teeth’ had a lower risk of CVD (HR = 0.4; 95%CI, 0.2–0.9). Some oral symptoms may be predictors of mortality from pneumonia and CVD.

Premature mortality due to stroke and trend in stroke mortality in Japan (1980-2005).

BACKGROUND Although a downward trend in stroke mortality over the last decades has been observed in many countries, stroke remains an important contributor to the total burden of disease. In the present study, we provided additional measures, namely years of life lost (YLLs) and average years of life lost (AYLLs) to reflect the burden of this condition in Japan. METHODS We obtained stroke mortality data for Japan from the World Health Organization mortality database for the period 1980-2005 to analyze trends of age-standardized rates (ASRs) per 100,000 of stroke mortality. YLLs and AYLLs were also estimated according to Japanese life tables. RESULTS Decreases in ASRs by 68% in men and by 74% in women were observed at the end of this study period. In men, there were total of 1,684,482 YLLs in 1980; 776,350 in 1995 and 745,636 in 2005, corresponding to an overall AYLLs for all stroke deaths of 20.6; 11.2 and 11.7 years earlier than expected, respectively. In women, the respective numbers were 1,567,817 YLLs in 1980; 810,135 in 1995 and 726,650 in 2005, corresponding to an overall AYLLs for all stroke deaths of 19.4; 10.5 and 10.5 years. CONCLUSIONS The findings showed shorter AYLLs due to stroke in Japan, suggesting that stroke patients died from this condition at older age at the end of the study period. This change in premature mortality was consistent with decreased trend in the stroke mortality.

Estimation of premature mortality from oral cancer in Japan, 1995 and 2005

BACKGROUND To better understand the picture of premature death from oral cancer, we estimated years of life lost (YLL) and average years of life lost (AYLL) of this cancer for the years 1995 and 2005 in Japan. METHODS We obtained the mortality data for 5-year age groups from the Vital Statistics of Japan for the years 1995 and 2005, an interval of 10 years. Age-standardized rates (ASRs) per 100,000 persons were calculated for each subset of oral cancer. We estimated YLL and AYLL according to life tables in Japan to reflect premature mortality. RESULTS For both men and women combined, 4099 and 5679 deaths due to oral cancer were recorded for the years 1995 and 2005. In men, cancer of tongue, oropharynx, and hypopharynx were the most frequently observed anatomic sites. We observed a total of 51,339.1 years of life lost in 1995 and 68,630.4 years in 2005, corresponding to an overall AYLL for all oral cancer deaths combined of 17.2 and 16.5 years earlier than life expectancy, respectively. The greatest AYLL was seen for deaths from nasopharyngeal cancer, with AYLL of 21.1 years in 1995 and 20.3 years in 2005. In women, cancer of the tongue and gum were the most affected anatomic sites. Total numbers of YLL were 18,884.8 years in 1995 and 24,765.7 in 2005, corresponding to an overall AYLL of 16.9 and 16.2 years earlier than life expectancy. The greatest AYLL was seen for deaths from nasopharyngeal cancer, with AYLL of 22.4 years and 20.4 years in 1995 and 2005, respectively. CONCLUSION The present study shows that cancer of pharynx, tongue, and gum were the most frequent oral cancers in both sexes in both 1995 and 2005, and responsible for a remarkable number of years of life expectancy lost. Deaths due to those cancer sites occurred about 16-21 years earlier than expected in men, and 14-22 years in women.

Relationship between serum levels of insulin-like growth factors and subsequent risk of cancer mortality: Findings from a nested case-control study within the Japan Collaborative Cohort Study

BACKGROUND We investigated the association between serum levels of IGF-I, IGF-II, and IGFBP-3 and the subsequent risk of cancer mortality. METHODS Our case-control study examined samples from 914 cancer deaths and their 2739 matched controls within the Japan Collaborative Cohort Study. Blood samples were obtained at the baseline and stored at -80 degrees C until analysis for IGF-I, IGF-II, and IGFBP-3 levels. The conditional logistic model was used to estimate odds ratios (ORs) for cancer mortality associated with these serum levels. RESULTS The adjusted ORs for IGF-I quartiles ranged from 0.81 to 0.96 but were not significant. The adjusted ORs and 95% confidence interval (CI) for the second, third, and fourth IGF-II quartiles were 0.64 (95% CI: 0.52-0.79), 0.71 (95% CI: 0.58-0.88), and 0.73 (95% CI: 0.59-0.91), respectively, while those for the respective IGFBP-3 quartiles were 0.77 (95% CI: 0.63-0.96), 0.75 (95% CI: 0.60-0.94), and 0.71 (95% CI: 0.56-0.90). In the model of IGF-I, and IGF-II additionally adjusted for IGFBP-3, the associations of high IGFs levels were similar as observed in the above models, while the association of IGFBP-3 shifted into non-significance after adjusting for IGF-II. CONCLUSION An increased level of IGF-II was significantly associated with decreased risk of cancer mortality, whereas the association between IGF-I and all cancer mortality was not significant. The inverse association of IGFBP-3 level with all cancer mortality was affected when adjusting for IGF-II levels, shifting from significant to non-significant. Confirmation of these results from further cohort studies may aid in identifying the potential association between these molecules and the risk of cancer among the general Japanese population.