More cancers than previously thought could be treated by drugs that are already available on the NHS, according to research.
Medicines such as trastuzumab (Herceptin) could have wider use, an analysis of tumour cells suggest. The drug is currently prescribed to people with breast cancer.
Lung cancer drugs erlotinib (Tarceva) and gefitinib (Iressa) could also present new opportunities.
Experts heard the evidence at a Berlin conference hosted by the European Organisation for Research and Treatment of Cancer, National Cancer Institute and the American Association for Cancer Research.
Scientists studied 22 genes targeted by existing therapies and found similarities to other cancer tumours.
All the tumours had five or more copies of a particular gene, making them mutated or "amplified" genes, which are implicated in tumour growth.
The researchers studied the genes in tumours taken from 4,086 patients.
They found 592 DNA amplifications in 438 cancer patients, suggesting between 5% and 10% of people with cancer may benefit from an existing treatment.
Cancers that could potentially be targeted include specific brain, breast, colon, lung, ovary and pancreatic cancers.
Dr Daniel Rhodes, Chief Executive Officer and co-founder of scientific applications at Compendia Bioscience, led the study.
He said: "We caution that we have not demonstrated that the targeted therapies will benefit all cancer patients with a DNA amplification, but we suspect, given past clinical trials and experimental studies, that some DNA amplifications will be predictive of therapeutic benefit for some patients."