Obesity is a growing problem all over the world. The incidence of obesity related disorders are increasing day by day and cancer is one of the dreadful complications in obesity related disorders.
Body mass index is the singular entity defining overweight and obesity. If BMI is more than 25 it is overweight and more than 30 is obese.
Obesity is a metabolic disorder affecting our body metabolism. Obesity leading sex hormonal changes, production of inflammatory markers affect many cancers in our body.
Obesity and ovarian cancer
Ovarian cancer is one of the critical cancers among women. The relationship between adiposity and ovarian cancer is well described in many studies. The low grade serous and high grade mucinous varieties are related to obesity. The exact mechanism related to this is unclear but the increased inflammatory biomarkers and hormonal factors are related to this. Future studies relating to weight loss and decrease in incidence is a matter of debate. Higher BMI may be associated with certain histologic subtypes, including low grade serous and invasive mucinous cancers. Increased levels of estrogen may be important in development of higher grade of mucinous tumors. future research should focus on key tumour characteristics with change in weight pattern in relationship with ovarian cancer risk with survival.
Obesity and endometrial cancer
Endometrial cancer is very strongly associated with obesity. In US, more than 50% endometrial cancers are associated with overweight and obesity. Endometrial cancer is very common in postmenopausal women. The key factors related to this are increased sex steroid hormone production, inflammatory markers, insulin resistance, adipokines are causative factors. Different studies regarding lifestyle modifications are under intense research to determine whether modifications of these factors could lead to decrease incidence of these cancers. BMI between 30 to 35 is associated with 2.5 times more morbidity and BMI more than 40 is associated with 6.2 times more morbidity of endometrial cancer.
Obesity and prostate cancer
The link between obesity and prostate cancers is complex and heterogeneous. Particularly prostate specific antigen(PSA) level and incidence due to related factors like insulin like growth factors (IGF), sex steroid hormones are possible linkage in the complex heterogeneous factors.
Obesity and breast cancers
Breast cancer is a leading cancer particularly in developed countries. The incidence is ever increasing day by day due to the faulty lifestyle factors and obesity. The prognosis depends on estrogen receptor (ER +ve) or progesterone receptor (PR +ve) among obese patients. Estrogen cause proliferation of glandular and epithelial cells of breast.
The association of postmenopausal breast cancer risk with obesity is dependent on ER +ve breast cancers. Many studies have outlined the relationship in many case control and cohort studies. The association is stronger in women of Asia pacific than those in North America, Europe and Australia.
Hepatic cancer
Rising incidence of non alcoholic steatohepatitis along with lifestyle factors have contributed to liver carcinoma. In obesity metabolic factors augment the process in form of increased insulin resistance, raised IGF-1 levels, inflammatory markers, chemokines, adipokines. All these factors have manifold aggravated the prevalence of hepatic cancers.
Obesity is frequently associated with chronic liver diseases and these cases may be associated with hepatocellular carcinoma risk. A healthy diet and lifestyle may reduce the chances of these hepatic carcinoma. Still more extensive studies required to find the definitive association.
Obesity and colon cancer
Faulty food habits like increased intake of saturated fats and lack of exercise are predominant factors related to obesity which affect the incidence of colon cancers. The increased intake of red meat has been a risk factor in colon carcinoma. Obesity also increases the propensity for development of neoplastic polyps which are pre cancerous lesions of colon cancer. Weight reduction has been associated with reduced incidence of neoplastic polyps and colon cancer.
Obesity and physical inactivity are strong determinants of insulin resistance. A diet high in refined sugars and low in fiber are often associated with colon cancers and hyperinsulinemia. These lead to increased free insulin like growth factor 1(IGF-1) levels. IGF-1 are associated with decreased cell death and increased cellular proliferation like a procarcinogen. IGF-1 linked to the development, progression and metastatic potential of colon cancers.
Obesity and kidney cancers
Obesity is also one of the established risk factors for renal cell cancers. Many case control and cohort studies have found a relationship between obesity and renal cell carcinoma.
