In the UK, more than 4,000 women die each year from ovarian cancer, with 65% of these deaths caused by High Grade Serous Cancer (HGSC) - the most common type of ovarian cancer. Although chemotherapy can be very effective at treating HGSC type of ovarian cancers at the beginning, these tumors often stop responding to the treatment over time.
With funding from the Association for International Cancer Research (AICR), Dr. Prue Cowin and Dr David Bowtell in collaboration with the Peter MaCallum Cancer Center (Peter Mac) in Melbourne, Australia, have discovered a gene that seems to play a vital role in HGSC tumors becoming resistant to chemotherapy.
Dr Bowtell, Head of the Cancer Genomics Program at Peter Mac, explained:
"We were interested in identifying the molecular changes that occurred in a tumor between the time when a woman was first treated, with surgery and chemotherapy, and the time when the tumor recurred and eventually became resistant to chemotherapy."
For the study, 22 women suffering with HGSC type of ovarian cancer gave samples of their tumors prior to, and after they received treatment with chemotherapy. After examining the samples, the team found that the genes within the cancer cells had dramatically changed between the two sets of samples being taken.
According to the team, the most dramatic changes occurred in tumors that had initially responded well to chemotherapy, but later because resistant to it. The most frequent genetic change usually caused a reduction in the levels of a protein called LRP1B. In lab studies, researchers have found that this protein helps prevent cancerous cells from growing.
Dr. Prue Cowin, who conducted a large part of the study, explained: "We were surprised by how much variation we found between the tumor samples that we collected during surgery, and the samples that were collected after the tumors returned. This provides the cancer with many ways to become resistant to chemotherapy, and may help explain why it has been so difficult to make progress with this disease."
Dr Gwen Wathne, Science Communications Manager at AICR, concluded:
"Resistance to chemotherapy is a huge problem for many people affected by cancer and an enormous challenge for cancer researchers to solve. We are delighted to have funded this study, which reveals one of the reasons why this happens in the most common type of ovarian cancer. We hope that this line of research will one day help doctors predict which ovarian cancers are likely to become resistant to chemotherapy, leading to an improvement in treatment for the estimated 225,000 (7000 in the UK) women who are diagnosed with the disease worldwide every year."