The team led by Andy Minn at the University of Chicago have found that many cancers show abnormalities in 49 genes, collectively known as the IFN-related DNA damage resistance signature (IRDS).
After analysing 34 different cancer cell lines and several hundred primary human cancers, the researchers found that IRDS was linked to radiotherapy resistance.
However, in breast cancer patients, the genetic signature could correctly envisage which cancers would be resistant to chemotherapy.
"This moves us one step closer to personalising cancer treatment, and points towards ways to improve the effectiveness of chemotherapy and radiotherapy," New Scientists quoted a spokeswoman for Cancer Research UK (CRUK) as saying.
On the other hand, research team led by Jason Carroll at CRUK's Cambridge Research Institute found how breast cancers become resistant to the drug tamoxifen.
The team suggests that the new discovery may help in developing new drug and ways of predicting which patients are unlikely to respond to tamoxifen.
The new study appears in Proceedings of the National Academy of Sciences.