The "Obesity Paradox" Where Higher Survival Rates Occur with More Obesity... "Acts Differently by Gender in Stomach Cancer"

Bundang Seoul National University Hospital Professor Kim Nayoung's Research Team
Higher BMI Linked to Better Prognosis in Men
No Clear Trend Observed in Women

Professor Kim Nayoung (left) of the Department of Gastroenterology at Bundang Seoul National University Hospital, and Professor Cho Hyeongho of the Department of Gastroenterology at Daegu Catholic University Hospital.

[Asia Economy Reporter Lee Gwan-joo] A study has found that the so-called "obesity paradox," where being overweight lowers the risk of death and extends life expectancy in certain diseases, shows differences by gender in gastric cancer.

Professor Kim Na-young of the Department of Gastroenterology at Bundang Seoul National University Hospital and Professor Jo Hyung-ho of the Department of Gastroenterology at Daegu Catholic University Hospital announced on the 9th that changes in gastric cancer survival rates according to obesity levels and pathophysiological patterns appear differently in men and women.

The obesity paradox is considered a representative paradox in the medical community. Since the term first appeared in the 1990s until today, especially in the field of cancer, studies have shown that higher body weight is positively associated with survival. However, some argue that the exact mechanism has not been clarified and remains hypothetical.

The research team conducted a study analyzing the association between survival rates and factors such as age, gender, and body mass index (BMI) in 14,688 patients diagnosed with gastric cancer at Bundang Seoul National University Hospital from 2003 to 2020. As a result, it was found that the survival rate was lowest in the underweight patient group for both men and women. However, while prognosis improved progressively in men as they moved into the 'extreme obesity' group, this trend was not clearly observed in women.

Additionally, in men, the incidence of cardia gastric cancer (the area where the stomach and esophagus meet) showed a U-shaped pattern, decreasing as BMI increased from underweight to obese, then rebounding in the extreme obesity group (BMI 30 kg/m² or higher). However, this association was not observed in women. Unlike men, women showed a continuous decrease in the proportion of diffuse-type gastric cancer (a form where small cancer cells infiltrate widely into the stomach wall) as BMI increased. Diffuse-type gastric cancer is classified as the most dangerous form due to its rapid progression and difficulty in treatment.

This study demonstrates that the obesity paradox, where increased body weight positively affects survival rates, manifests differently between men and women, and also suggests that the mechanisms by which obesity influences cancer survival rates differ by gender.

Professor Kim said, "In analyses of all patients, as well as detailed analyses by surgery status and cancer stage, survival rates increased proportionally with higher BMI in men, whereas this trend was not clear in women. If we study these gender differences in gastric cancer prognosis and patterns more deeply, it will help clarify the exact principles of the 'obesity paradox' and advance gastric cancer treatment methods."

The study results were published in the recent issue of the SCI(E)-level international journal Gut and Liver.

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