JEDDAH, 2 May 2007 — Genetic factors play a significant role in causing many diseases including cancer, according to Dr. Mouhammed Kelta, acting chairman of the Department of Oncology at the King Faisal Specialist Hospital and Research Center in Jeddah.
“Many, if not most, diseases have their roots in our genes. More than 4,000 diseases stem from altered genes inherited from one’s mother or father,” he told Arab News. Dr. Kelta said common disorders such as heart disease and most cancers arise from a complex interaction between genes and environmental factors.
Breast cancer among women is a No. 1 malignancy not only in Saudi Arabia but also globally. “It represents almost 20 percent of all cancers diagnosed among women in the Kingdom,” Kelta said. During 2001-2005 Kelta’s department treated 500 cases of breast cancer, 260 cases of colon cancer and 44 cases of ovarian cancer.
“Most cancers are caused by mutations that develop in the cells of a person either as a mistake when cells undergo division or as a result of injuries caused by environmental agents including radiation and chemicals,” he explained.
Kelta said genetic mutations make some individuals more susceptible to developing certain types of cancer. “Inherited alterations in genes can cause breast and ovarian cancers,” he added.
For example, women with breast cancer susceptibility genes have an 80 percent chance of developing breast cancer by the age of 65. “Women with an altered BRCA1 or BRCA2 gene are three to seven times more likely to develop breast cancer than women without alterations in those genes,” he added.
However, Dr. Kelta said most women do not get the inherited type of breast cancer. “About 10 to 15 percent of all breast cancers are thought to be familial and only two-thirds to three-fourths of these cases are due to an inherited mutation,” he said.
Having breast cancer in two or more first-degree relatives (mother, sisters and daughters) may cause other members of the family to also catch the disease. “Another sign of a risk of inherited breast cancer is a first-degree relative who got breast cancer before she was 50 years old,” he said. Having a first-degree relative with ovarian cancer might also mean increasing the risk of carrying breast cancer gene.
He added that both the paternal and maternal sides of the family contribute to the increased risk of developing cancer, but marriage between relatives per se does not.
Dr. Kelta advised known carriers (those who have gene alteration) to examine themselves on a monthly basis at the age of 18 and annual clinical examination at the age of 25. Annual mammography is also recommended from the age of 25, he added.
Kelta emphasized the importance of early diagnosis in treating cancer. “Knowing an individual is at increased risk of developing cancer may have life-saving management implications and may lead to specific interventions aimed at reducing risk,” he pointed out. For example, women at increased risk of developing breast cancer may seek medical advice to consider one of the preventive measures such as taking Tamoxifen pills (opposing estrogen) or even prophylactic mastectomy (surgical removal of the breast).