Scientists at Cancer Research UK have discovered why so many cancer patients relapse into their cancer after chemotherapy treatments and why, even after numerous rounds of treatment, the cancer returns.
They studied women suffering from ovarian cancer, a type of cancer that can be notoriously difficult to treat. The survival rate for women with ovarian cancer who have had chemotherapy for their treatment is less than 35 percent at five years after the treatment, even if they initially seemed to respond well.
The scientists theorized that this may be because the patients were becoming resistant to chemotherapy drugs in the same way that we become resistant to antibiotics if we have too many doses, but they discovered that the actual cancer cells grew with resistance built in, shielding them from the killing effects of chemotherapy.
Dr. James Brenton, study author, 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 tumor.
“By examining the characteristics of ovarian tumours we now think that cells resistant to chemotherapy grow as part of the tumor. This means that when patients have treatment, cells that respond to chemotherapy are destroyed but this leaves behind resistant cells which then form another tumor 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.”
Source: Genomic analysis of genetic heterogeneity and evolution in high-grade serous ovarian carcinoma by Cooke and Brenton et al. Oncogene.
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting, in addition to running a charity for people damaged by vaccines or medical mistakes.