Fat surrounding tumor cells accelerates the development of cancer, according to a new study. Researchers said that the latest findings may offer insights into novel breast cancer treatments and explain why obese people are more likely to develop breast cancer and why their cancers are generally more aggressive.

Researchers from the University of Granada found evidence that peritumoral fat, or fat around the tumor, speeds the onset and growth of tumors by aiding the development and invasion of cancer stem cells.

Only tiny amounts of cancer stem cells are found in tumors, but traditional treatments like chemotherapy and radiotherapy are currently unable to kill off cancer stem cells. Researchers believe that the effect of cancer stem cells, which are responsible for the spread of cancer from the original tumor, can explain why many patients suffer relapse after treatment.

Previous research revealed that obese women have a significantly greater risk of suffering breast cancer after menopause. Obese women are also more likely to suffer more aggressive cancers, even after accounting for age. But why? Researchers in the latest mouse study believe the answer may lie with obesity-related fat after coculturing fat cells with cancer cells.

Researchers explain that obesity-related fat prevents adiopocytes from maturing, and immature adiopocytes interact with tumor cells to create cytokins, also called proinflammatory proteins. These cytokines then make it easier for highly metastatic cancer stem cells to reach other parts of the body.

"The prolonged coculture of tumor cells with immature adipocytes or cytokines increased the proportion of cancer stem cells (which had the ability to form new tumors), the presence of tumor cells in blood, and the metastatic potential after its implementation in mice. And last, we found that SRC-Kinase-inhibiting drugs decrease the production of cytokines and cancer stem cells," co-study author Juan Antonio Marchal Corrales of the University of Granada said in a university release.

Researchers said the latest findings suggest that SRC inhibitors could be used for for breast cancer treatment.

"These data support a model in which cancer cell invasion into local fat would establish feed-forward loops to activate Src, maintain proinflammatory cytokine production, and increase tumor-initiating cell abundance and metastatic progression. Collectively, our findings reveal new insights underlying increased breast cancer mortality in obese individuals and provide a novel preclinical rationale to test the efficacy of Src inhibitors for breast cancer treatment," the researchers concluded.

The latest findings are published in the journal Cancer Research.