Exploring the association of birth weight and early -onset cancer, with an emphasis on breast cancer

There is evidence from previous studies that birth weight, either high or low, may be a risk factor for certain cancers. This thesis explores this relationship in a number of ways. A case-control study is used to explore whether a relationship is evident in 117 individuals of either African American or Caucasian race diagnosed with cancer prior to age 46 years. Each case has two individuals matched on gender, race, and year of birth chosen from the birth certificate registry to serve as birth weight controls. A relationship between high birth weight and cancer is identified. Further analysis is conducted to determine which specific types of cancer are responsible for the relationship. Although numbers are small, lymphoma, lung, and breast cancer show the strongest relationship to birth weight. Building on the results of that study, a case-control study is conducted to explore whether a relationship is present between birth weight and breast cancer in 125 individuals of either African American or Caucasian race diagnosed prior to age 50 years. Three controls were chosen as above for each case. Individuals in the lower than average birth weight category are at reduced risk of breast cancer compared to the individuals in the average birth weight category. These cases are also used in a cross-sectional study to determine whether certain prognostic factors are related to birth weight. The individuals with worse prognosis consistently have higher mean birth weights than the individuals with better prognosis. Women diagnosed with node positive breast cancer have a significantly higher mean birth weight than those diagnosed node negative. Finally, ecological studies are conducted utilizing a geographic information system to explore the relationship between birth weight and early-onset breast cancer on a county level, as well as between birth weight and advanced early-onset breast cancer on a state level. The county level study does not provide further evidence of a relationship between high birth weight and early-onset breast cancer, but the state level study does show evidence of a relationship between high birth weight and diagnosis of node positive breast cancer.