In a breakthrough which may pave the way for personalised cancer treatment, scientists claim to have discovered the genetic reason why the disease responds to normal chemotherapy in some patients, but resistant in others.

An international team, led by Andrea Richardson and Zhigang Charles Wang of the Dana-Farber Cancer Institute, has identified two genes which, when abnormally active, enable cancer cells to resist effects of drugs called anthracyclines.

The scientists examined specimens from 85 patients and found the gene signature associated with drug resistance in about one in five samples, according to their report in the ‘Nature Medicine’ journal.

Clinical records on file showed that those patients had poorer outcomes than those without the culprit gene signature. However, the over expression of the two genes did not protect laboratory-grown breast cancer cells against other classes of drugs like paclitaxel and cisplatin, it said.

“These results suggest that tumours resistant to anthracyclines may still be sensitive to other agents. So this would be very useful as a test to help pick the therapy that’s going to be most effective for these patients,” Dr. Richardson was quoted by ‘The Daily Telegraph’ as saying.

Such a tool should not be difficult to develop and could be available for clinical testing within a year or two, she said.

The team sifted the tumour DNA and spotted a region on chromosome 8 that contained many redundant, or amplified, copies in the drug-resistant tumours. They found that two genes labelled LAPTM4B and YWHAZ appeared to signal resistance to treatment, the report said.