Houston, Texas, USA : Overweight adolescents risk pancreatic cancer and/or colorectal cancer later in adulthood researchers report in separate studies.
In the first study new research has linked adolescent obesity with up to a four-fold increased risk of pancreatic cancer later in life. The study’s results also suggest that overweight and even higher weight within the “normal” weight range in men may increase pancreatic cancer risk in a graded manner. The findings are published early online in Cancer.
Pancreatic cancer is the sixth most common cause of cancer-related deaths in the world, and studies have linked adult obesity with an increased risk for its occurrence. To uncover any potential associations with adolescent weight, Zohar Levi, MD, of Rabin Medical Center and Tel Aviv University, and his colleagues analyzed 1,087,358 Israeli Jewish men and 707,212 Jewish women who underwent a compulsory physical examination between the ages of 16 and 19 years from 1967 to 2002. Pancreatic cancer incidence through 2012 was identified by linkage to the Israeli National Cancer Registry.
Over a median of 23.3 years of follow up, 551 new cases of pancreatic cancer cases were identified, including 423 cancers among men and 128 cancers among women. Compared with normal weight (5th to <85th percentile), obesity (?95th percentile) was associated with a 3.67-times higher cancer risk among men and a 4.07-times higher risk among women.
Among men, high-normal BMI (?75th to <85th percentile) and overweight (85th to <95th percentile) were associated with 49 percent and 97 percent higher risks for cancer, respectively, compared with low-normal BMI (?5th to <25th percentile).
“The overall population attributable fraction of pancreatic cancer due to adolescent overweight and obesity was 11 percent among this Israeli Jewish population,” said Dr. Levi.
An accompanying editorial by Chanan Meydan, MD, of the Mayanei Hayeshua Medical Center in Israel, highlights systemic inflammation caused by obesity as a potential driver behind the development of pancreatic cancer.
Citation: “Adolescent overweight and obesity and the risk for pancreatic cancer among men and women. A nationwide study of 1.79 Million Israeli adolescents.” Zohar Levi, Yakir Rottenberg, Gilad Twig, Lior Katz, Adi Leiba, Estela Derazne, Dorit Tzur, Sapir Eizenstein, Lital Keinan-Boker, Arnon Afek, and Jeremy D Kark. CANCER. DOI: 10.1002/cncr.31764
A second study has uncovered a link between being overweight or obese in adolescence and an increased risk of developing colon cancer in adulthood.
Obesity was also associated with an elevated risk of developing rectal cancer. Published early online in Cancer, a peer-reviewed journal of the American Cancer Society, the findings come at a time of growing concern about the impact of adolescent overweight and obesity on chronic disease later in life.
Study results on a potential link between adolescent obesity and the risk of colorectal cancer are conflicting, and many of the studies’ designs have been limited. To provide more clarity, Zohar Levi, MD, of the Rabin Medical Center and the Tel Aviv University in Israel, and his colleagues analyzed information on 1,087,358 Jewish males and 707,212 Jewish females who underwent health examinations, including measures of body mass index (BMI), at age 16 to 19 years (predominantly aged 17 years) between 1967 and 2002. Individuals were followed to 2012.
Over a median follow-up of 23 years, 2967 new cases of colorectal cancer were identified, including 1977 among men (1403 colon, 574 rectum) and 990 among women (764 colon, 226 rectum). Overweight and obesity were associated with 53% and 54% higher risks of colon cancer for men and women, respectively. Obesity was associated with a 71% increased risk of rectal cancer in men and more than a twofold increased risk in women.
“This is a huge cohort with a minimum follow up of 10 years, and all individuals had measured BMI, not just reported or recalled,” said Prof. Levi. “This is the largest study ever, including both men and women, and it had the power to prove the importance of BMI at age 17 on events later in life.”
The main limitation of the study is that the cohort was still young, with the median age at colorectal cancer diagnosis of 49.4 years. The study also lacked data on diet, physical activity, and smoking, which might affect risk estimates. Family history of colorectal cancer was also unknown.
Citation for second study: Zohar Levi et al, Adolescent body mass index and risk of colon and rectal cancer in a cohort of 1.79 million Israeli men and women: A population-based study, Cancer. DOI: 10.1002/cncr.30819
A third study found overweight boys to be at greater risk of colon cancer as adults, but losing weight may modify the risk.
Overweight boys at greater risk of colon cancer as adults
New research presented at the European Congress on Obesity (ECO) in Porto, Portugal suggests that overweight boys may be at greater risk of colon (bowel) cancer when they grow up than their slimmer friends. However, overweight boys who shed the pounds and achieve a healthy weight by young adulthood do not appear to be at increased risk of colon cancer as adults. The findings underline how important it is for children to be a healthy weight.
Colon cancer is the 4th most common cancer in adults, with around 41,000 cases diagnosed each year in the UK. Previous research shows that overweight children are at higher risk of colon cancer as adults, but it is unclear whether changes in body mass index (BMI) between childhood and young adulthood alter this risk.
In this study, Dr Britt Wang Jensen and Associate Professor Jennifer Baker from Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark and colleagues analysed the health records of over 61,000 Danish school boys born between 1939 and 1959, to examine how changes in BMI in childhood and young adulthood are associated with colon cancer risk in adulthood. Participants’ weight and height were measured at age 7 years and in young adulthood (age 17-26 years) and BMI was calculated. These young men were then linked with the Danish Cancer Register and followed from the age of 40 years to identify cases of colon cancer.
During an average (median) 25-year follow-up, more than 700 boys went on to develop colon cancer. Analyses showed that boys who were overweight (BMI greater than 17.88 kg/m2) at age 7 years but normal weight (BMI under 25.0 kg/m2) as young men had similar risk of adult colon cancer as those who maintained a stable, healthy weight throughout. In contrast, overweight boys who remained overweight as young men had twice the colon cancer risk. The study took educational level into account but not lifestyle factors that might contribute to a person’s risk of developing cancer.
The authors conclude: “Overweight boys that lose weight and achieve a normal-weight status by young adulthood do not carry an increased risk of adult colon cancer compared with boys who remain normal-weight as young men. However, overweight boys who remain overweight as young men have an increased risk of adult colon cancer. These results highlight the importance of weight management in childhood.”
They add: “Our next steps are to expand our focus and examine other forms of cancer along with other non-communicable diseases to create a full picture of how a man’s weight development across his life, even from birth, is associated with his risk of disease.”