Chemotherapy-resistant ovarian tumour cells "re-grow" cancer

Cancer Research UK scientists have discovered certain ovarian tumour cells that are resistant to chemotherapy can survive a first round of treatment and go on to "re-grow" the cancer. This could help explain why the disease can be difficult to treat, according to new research published in Oncogene yesterday, 28 June 2010.

The study, funded by Cancer Research UK, aimed to find out whether it is the chemotherapy itself that causes anti-cancer drug resistance to build in the body - similar to resistance to antibiotics - or if cells that are shielded against cancer treatment grow as part of the initial tumour and are already lying dormant before chemotherapy begins.

Often ovarian cancer can be hard to treat with treatment failing after women initially responded well. The number of women surviving beyond five years is less than 35%.

Ovarian cancer notoriously hard to treat

The researchers compared the characteristics of cell lines from the tumour at the time of diagnosis to cell lines from the same patients once the disease had been treated and become resistant.

Dr James Brenton, study author from the Cancer Research UK's Cambridge Research Institute, said: "Ovarian cancer is notoriously hard to treat. Women usually respond well to their first round of chemotherapy with the disease apparently completely removed. But unfortunately many go on to relapse within six to 24 months. Until now we haven't known whether they are becoming resistant to the treatment or whether the cells that don't respond to treatment re-grow the tumour.

"By examining the characteristics of ovarian tumours we now think that cells resistant to chemotherapy grow as part of the tumour. This means that when patients have treatment, cells that respond to chemotherapy are destroyed but this leaves behind resistant cells which then form another tumour of completely resistant cells. This seems to explain why successful treatment for relapsed patients is difficult. What needs to be developed now is a therapy designed to target the resistant cells."

Dr Lesley Walker, director of science information at Cancer Research UK, said: "Discoveries like this help to tell us why chemotherapy stops working for some ovarian cancer patients. We hope it will lead to new ways to tackle the disease and increase the number of women that survive this cancer that can be so hard to cure. The next step will be to develop treatment tailored to fight the resistant cells."

Source: Cancer Research UK