Hi Summer. Very sad story for sure. I'm unaware of any association between obesity and lymphoma. There have been postulated links between fat intake and breast cancer but the evidence is very tenuous. Obesity is certainly a risk factor for cancer of the endometrium (the inner lining of the uterus) but most of the time these obesity-related cancers are low-grade and cured by hysterectomy. Otherwise I'm drawing a blank.
Obesity is certainly related to diabetes, heart disease and a host of other medical problems but I think the cancer link is less of an issue.