Pharmaceutical company Roche recently launched an important milestone making its targeted therapy bevacizumab available for a disease where few treatment advances have been seen in over two decades.
The Philippine Food and Drug Administration (FDA) approved the use of bevacizumab in combination with standard chemotherapy (carboplatin and paclitaxel) as a front-line treatment for women with advanced ovarian cancer.
Ovarian cancer is the most deadly of the gynaecological cancers and approximately 140,000 women die from the disease each year.
It is the second leading cause of death from gynaecologic cancer in the Philippines and the country’s seventh most common cause of cancer mortality in women.
In 2010, there were an estimated 2,165 new diagnoses and an estimated 1,016 deaths from ovarian cancer in the Philippines.
The incidence rate rises steeply starting at age 40 and continues to increase with age.
The Society of Gynecologic Oncologists of the Philippines (SGOP) welcomed the news and the results of clinical trials supporting the use of bevacizumab as first-line treatment for ovarian cancer.
In a setting with few advances in the last decades, bevacizumab has demonstrated in two phase III studies (GOG 0218 and ICON 7) that women who received the combination of bevacizumab and chemotherapy and then continued on bevacizumab alone, lived significantly longer without their disease getting worse (progression-free survival) compared to those who received chemotherapy alone.
"Three major clinical trials have shown that standard chemotherapy plus bevacizumab significantly improves the time women with ovarian cancer live without the disease getting worse compared to those on standard chemotherapy alone," said Dr. Efren J. Domingo, past President of SGOP and Chief, Section of Gynecologic Oncology, St. Luke’s Medical Center Global City.
A treacherous disease
Like in other forms of cancer, the prognosis for ovarian cancer patients is poor, particularly when the disease is diagnosed in its later stages.
Unfortunately, majority of patients are diagnosed with ovarian cancer when the disease is already in its advanced stages.
According to Dr. Domingo, there are several reasons why ovarian cancer is very difficult to diagnose.
"Symptoms for ovarian cancer are non-specific and could be attributed to any other conditions. Common symptoms include persistent bloating, abdominal pain, irregular menstrual periods, loss of appetite, change in bowel movements, constipation, flatulence, and abnormal vaginal bleeding. These manifestations can be confused with symptoms of other less severe diseases, such as gastrointestinal complaints. Indeed, ovarian cancer symptoms are so ambiguous that the disease is often misdiagnosed. Ovarian cancer is a treacherous disease."
The anatomical location of the ovaries is also a factor.
"Unlike the cervix which sits low in the vaginal canal and easily accessible for examination, the ovaries are located high up in the abdominal cavity and are quite difficult to examine," Dr. Domingo explained.
Also, he continued, in contrast to cervical cancer, ovarian cancer does not develop a pre-cancerous lesion, which can serve as an early warning sign before the cancer becomes invasive.
Lastly unlike other forms of cancer (e.g., cervical cancer can be detected early through regular Pap examination), there is no routine, simple test to accurately and reliably detect ovarian cancer in the general population so reliable screening for the disease is not yet feasible.
Ideally, Dr. Domingo said, diagnosing ovarian cancer requires a "triad of tests": a pelvic examination, a blood test called CA-125, and a pelvic ultrasound.
However, with the exception of a pelvic examination, these tests incur considerable cost and are usually available only in urban tertiary hospitals.
"For a test to become a routine screening tool, it must be universally available and affordable," Dr. Domingo explained.
Given the absence of an established screening tool for ovarian cancer, Dr. Domingo recommended women of reproductive age to undergo a yearly pelvic examination, which can detect an ovarian tumor in its early stage.
The following have an increased risk for ovarian cancer: women with a family history of ovarian, uterine and breast cancer, age over 50, women who have not had children, never taken the contraceptive pill, who started menstruating at an early age or whose menopause started later than average women who have previously had ovarian cysts or endometriosis, women who are obese, smoke and have a sedentary lifestyle.
Bevacizumab blocks tumor blood supply
For many years now, the standard of care for ovarian cancer treatment has been surgery and chemotherapy.
Ovarian cancer usually responds to chemotherapy but in the majority of cases the cancer returns (known as "relapse" or "recurrence"), resulting in half of patients eventually dying from the disease.
When the cancer returns, the only currently available treatment option is further chemotherapy.
"Three phase III clinical trials involving thousands of patients show standard chemotherapy plus bevacizumab provides definite benefits in terms of progression-free survival to patients with stage 3 and 4 ovarian cancer compared to those treated with standard chemotherapy alone," said Dr. Domingo.