Measures of birth size in relation to risk of prostate cancer: the Malmö Diet and Cancer Study, Sweden

Association of birth weight with cancer risk: a dose-response meta-analysis and Mendelian randomization study

BACKGROUND

Several articles have shown that birth weight is associated with the risk of many types of cancers. However, the results are inconsistent, and whether the relationship has a causal effect remains unknown.

METHODS

We searched the PubMed and Embase libraries up to March 2021 and selected observational studies reporting the relationship between birth weight and adult-onset cancer risk. Dose-response meta-analysis and two-sample Mendelian randomization (MR) analysis were used to estimate the effect.

RESULT

In our dose-response meta-analysis, six cancers from 46 studies were found to have significant associations with birth weight. (Ovarian cancer: RR: 1.21, 95% CI 1.01-1.44; breast cancer: RR: 1.12, 95% CI 1.08-1.16; colorectal cancer: RR: 1.20, 95% CI 1.01-1.43; endometrial cancer: RR: 0.85, 95% CI 0.78-0.93; prostate cancer: RR: 1.27, 95% CI 1.01-1.61; testicular cancer: RR: 1.21, 95% CI 1.03-1.43). As birth weight increased, the slope of the dose-response curve of breast cancer increased continuously, and the curve of testicular cancer was U-shaped. In the MR study, seven cancers were included. Only invasive mucinous ovarian cancer was found to have a causal effect on birth weight (OR: 0.62; 95% CI 0.39-0.97), while other cancers did not.

CONCLUSIONS

Our findings suggest that birth weight are unlikely to have a casual effect on risk of cancers via the MR analysis, although the dose-response meta-analysis shows that there is a nonlinear relationship between birth weight and breast cancer and testicular cancer. More relevant researches are needed to further investigate their effect.

Is birthweight associated with total and aggressive/lethal prostate cancer risks? A systematic review and meta-analysis

Background:

It has been hypothesised that intrauterine exposures are important for subsequent prostate cancer risk. Prior epidemiological studies have used birthweight as a proxy of cumulative intrauterine exposures to test this hypothesis, but results have been inconsistent partly because of limited statistical power.

Methods:

We investigated birthweight in relation to prostate cancer in the Medical Research Council (MRC) National Survey of Health and Development (NSHD) using Cox proportional hazards models. We then conducted a meta-analysis of birthweight in relation to total and aggressive/lethal prostate cancer risks, combining results from the NSHD analysis with 13 additional studies on this relationship identified from a systematic search in four major scientific literature databases through January 2015.

Results:

Random-effects models found that per kg increase in birthweight was positively associated with total (OR=1.02, 95% confidence interval (95% CI)=1.00, 1.05; I²=13%) and aggressive/lethal prostate cancer (OR=1.08, 95% CI=0.99, 1.19; I²=40%). Sensitivity analyses restricted to studies with birthweight extracted from medical records demonstrated stronger positive associations with total (OR=1.11, 95% CI=1.03, 1.19; I²=0%) and aggressive/lethal (OR=1.37, 95% CI=1.09, 1.74; I²=0%) prostate cancer. These studies heavily overlapped with those based in Nordic countries.

Conclusions:

This study provides evidence that heavier birthweight may be associated with modest increased risks of total and aggressive/lethal prostate cancer, which supports the hypothesis that intrauterine exposures may be related to subsequent prostate cancer risks.