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Serum cholesterol and mortality among Japanese-American men. The Honolulu (Hawaii) Heart Program
G N Stemmermann1, P H Chyou, A Kagan
1Japan-Hawaii Cancer Study, Honolulu 96817.
Insights
Serum cholesterol levels show a U-shaped relationship with mortality in Japanese-American men. Optimal health is linked to moderate cholesterol levels, with low levels increasing cancer risk and high levels increasing heart disease risk.
Area of Science:
- Epidemiology
- Cardiovascular Disease Research
- Oncology
Background:
- Serum cholesterol levels are a known risk factor for cardiovascular disease.
- Previous studies have suggested an inverse relationship between cholesterol and cancer mortality, but findings are inconsistent.
- Understanding the complex relationship between serum cholesterol and overall mortality is crucial for public health.
Purpose of the Study:
- To investigate the long-term relationship between baseline serum cholesterol levels and all-cause, cancer, and coronary heart disease mortality.
- To examine the distribution of death rates across different serum cholesterol levels in a cohort of Hawaiian men of Japanese ancestry.
- To determine if specific cancer types are associated with low serum cholesterol levels.
Main Methods:
- A prospective cohort study of Hawaiian men of Japanese ancestry with a follow-up of 18 or more years.
- Analysis of baseline serum cholesterol levels and subsequent mortality data.
- Statistical analysis to assess the relationship between cholesterol levels and mortality, including quadratic distributions and time-dependent associations.
Main Results:
- A quadratic distribution of death rates was observed across serum cholesterol levels.
- Mortality from coronary heart disease increased with rising cholesterol, while cancer mortality decreased.
- Low serum cholesterol (<4.65 mmol/L) was associated with increased cancer mortality, particularly for colon and lung cancers.
- The lowest overall mortality was observed in men with serum cholesterol levels between 4.65 and 6.18 mmol/L (180-239 mg/dL).
Conclusions:
- There is a U-shaped relationship between serum cholesterol and overall mortality in this cohort.
- Maintaining serum cholesterol levels within a moderate range appears optimal for reducing overall mortality risk.
- Aggressively lowering cholesterol below 4.65 mmol/L may increase the risk of death from cancer or other diseases.
Abstract:
Hawaiian men of Japanese ancestry followed up for 18 or more years after a baseline examination showed a quadratic distribution of death rates at different levels of serum cholesterol. Mortality from cancer progressively decreased and mortality from coronary heart disease progressively increased with rising levels of serum cholesterol. There was a positive association between baseline serum cholesterol levels and deaths from coronary heart disease at 0 to 6 years, 7 to 12 years, and 13 years and longer after examination. The inverse relationship between cancer and serum cholesterol levels was stronger in the first 6 years than in the next 6 years and, although still inverse, lost statistical significance after 13 years. Cancers of the colon and lung showed the strongest association with low baseline serum cholesterol levels, while gastric or rectal cancer failed to show this association. Organ specificity and persistence of the inverse association beyond 6 years suggest that the nutritional demands of cancers may not entirely explain the inverse association with some cancers. The quadratic distribution of deaths in this cohort remained after coronary heart disease, stroke, and cancer were removed from the analysis. For the entire period of observation, the lowest mortalities were found in men with serum cholesterol levels between 4.65 and 6.18 mmol/L (between 180 and 239 mg/dL). Manipulation of serum cholesterol levels below this level would not be desirable if this were to result in increased risk of death from cancer or other disease. This study does not rule out this possibility.