Growth Rate of Ovarian Tumors
Early Detection of Cancer Needs Sensitive Screening Test
Though ovarian cancer accounts for about 3% of all cancer, it is the fifth leading cause of cancer-related death in women. Among all ovarian cancer subtypes, epithelial ovarian cancer is the most common and represents 80% of all ovarian cancer. It is also the most lethal gynecological malignancy.
Due to its lack of symptoms, this disease is often detected and diagnosed at an advanced stage when the cancer has already spread into the body. In United States of America, ovarian cancer killed 15,520 women in 2007 and 21,000 deaths are predicted for 2008 while the number of new cases is around 21,600 per year.
Survival Rate of Patients with Epithelial Ovarian Cancer
If diagnosed at the early stage, when the tumor is still localized on the ovary, the survival rate of patients 5 years after diagnosis is 92%. However, since the disease is asymptomatic, the rate of patients detected at this stage of the disease represents less than 1 woman out of 5. In contrast, at the advanced stage of the disease, when the cancer has spread into the body and formed distant metastases, the survival rate of patients is below 30%. In average the survival rate of all ovarian cancer is below 40%.
Hereditary Ovarian Cancer
A small but significant proportion (5 to 10%) of ovarian cancer is due to the inheritance of genetic mutation, mainly in a gene named BRCA. Patients carrying a mutation in this gene have a 90% chance of developing ovarian or breast cancer. In these groups of patients if the genetic mutation is detected before the disease develops, removal of both ovaries will save the life of the patient. This procedure is named bilateral oophorectomies. This type of treatment is called prophylactic (preventive). Most of patients undergoing a prophylactic treatment have fortunately not yet developed the disease. In rare cases an unsuspected micro-cancer, visible only under microscopy, is discovered.
Progression Rate of Ovarian Cancer
Two scientists, Dr Patrick O Brown and Dr Chana Palmer, from Stanford University (Stanford, California, US) and the Canary Foundation (San Jose, California) have attempted to determine the rate of progression and growth in ovarian tumors. To this end, they studied several groups of patients with a BRCA mutation who underwent a prophylactic treatment and compared them to patients with BRCA mutation but with symptomatic tumors. The study is published in the scientific journal PLoS Medicine (vol 6, issue 7, e1000114) and entitled "The Preclinical Natural History of Serous Ovarian Cancer: Defining the Target for Early Detection".
Early Diagnosis Would Reduce by 50% the Death Rate of Ovarian Cancer
Dr Brown and Dr Palmer estimated that ovarian cancer develops for approximately 4 years at the early stage and less than 1 year at the advanced stage before becoming symptomatic. They also estimated than early stage tumors double in volume in 4 months, while advance stage tumors double in volume in 2.5 months. The researchers concluded that to detect only 80% of the patients with early stage cancer, a diagnostic test would need to detect tumors as small as 0.4 cm. Such a diagnostic test would reduce by 50% the death rate of ovarian cancer patients.
Tumor Growth
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