New discoveries challenge colon cancer

HAVING affected such global icons as Ronald Reagan and Cory Aquino, colon cancer is proving to be a fast-growing disease that can hit the high and the mighty, the poor and the lowly, at any place, at any time. But with the help of studies and the advent of newer technologies, researchers may finally put an end to this age-old cancer.

Colorectal cancer, a general medical term for both colon and rectal cancers, refers to malignant tumors that invade the intestinal walls and other organs of the body. The Department of Health classifies it as the fifth leading cause of death among Filipino males and females.

The colon is a part of the large intestine responsible for the further absorption of food nutrients and fluids from the small intestine, while the rectum, the final straight portion of the large intestine terminating in the anus, is where feces is temporarily stored before defecation.

According to the American Medical Association’s March 2008 journal, new studies reveal that previously ignored flat and depressed lesions in the intestine are more likely to turn cancerous than just polyps because of tendencies to be overlooked by clinicians, resulting in the late diagnosis of patients.

According to Dr. Felix Tambuatco, a resident colorectal surgeon at the UST hospital, in the past, polyps were the only accepted indication of a colorectal cancer.

“The new findings on flat lesions pose challenges for us physicians to be more alert and aware of these lesions along the intestinal walls,” he said.

Tambuatco also revealed that exact causes of colorectal cancer are not yet known, but several risk factors include undiagnosed formation of polyps in the intestine, a diet high in red meat, family history of cancer, and ulcerative colitis, a chronic inflammation of the colon.

Other predisposing factors for colorectal cancer identified by the UST Hospital-Benavidez Cancer Institute in their cancer-awareness posters and brochures include obesity, physical inactivity, diabetes, smoking, and excessive alcohol intake.

“Colorectal cancer symptoms are not noticeable during its early stages. But when symptoms start to appear such as a change in bowel habits for a couple of weeks with diarrhea, constipation, rectal bleeding, abdominal discomfort, unrelieved bowel movement, fatigue, and unexplained weight loss, patients are expected to readily consult a clinician,” Tambuatco said.

Innovative treatments

The three general treatments for colorectal cancer are chemotherapy, which uses drugs to stop the growth of cancer cells, radiation therapy which uses high-energy radiation to kill cancer cells, and surgical removal of the tumor/s.

Tambuatco said that depending on the stage, any or a combination of treatments can be used to kill any cancers left particularly to patients with severe colorectal cancer.

For decades, colorectal cancer medications were limited to two drugs, 5-fluorouracil and leucovorin, anti-cancer drugs used primarily for colorectal and pancreatic cancers in chemotherapy. But in 2004, a study published in the New England Journal of Medicine found that adding oxaliplatin, a platinum-based chemotherapy drug, with 5-fluorouracil and leucovorin, in a combination known as FOLFOX boosted patients’ survival rate by 11 per cent.

“We use this combination (FOLFOX) in the UST Hospital as part of the post-treatment protocol of patients diagnosed with colorectal cancer,” Tambuatco said.

Targeted therapies also came in 2004 which introduced bevacizumab and cetuximab, new-generation anti-cancer drugs that target specific tumors, resolving the side-effects of conventional chemotherapy procedures which kill both cancerous and healthy cells.

Bevacizumab is modeled after antibodies that naturally protect the body against harmful foreign bodies or substances. It prevents tumors from growing new blood vessels which prompt tumors to die easily.

Meanwhile, cetuximab blocks the effects of epidermal growth factor responsible for cell growth and divisions to prevent proliferation of cancer cells.

Another emerging new treatment endorsed by America’s National Cancer Institute is biologic therapy or immunotherapy. This procedure uses the patient’s immune system to fight cancer cells by boosting the patient’s natural defenses through laboratory substances such as vaccines and man-made proteins.

Prevention

But early detection of disease often leads to the best chance for cure. The Philippine Cancer Society recommends regular screening procedures for men and women beginning at age 40 for early detection of colorectal cancer.

Screening procedures include yearly fecal or occult blood tests which check for hidden blood in the stool, sigmoidoscopy—a visual examination of the colon in search of polyps every five years, regular digital rectal examination wherein the patient’s rectum is directly examined for lumps or growths, x-rays using barium sulfate injected into the rectum in search for polyps every five years, and colonoscopy which examines the rectum and colon using a lighted tube with a camera attached on it every 10 years.

“The only way to improve treatments of colorectal cancer is through early diagnosis of patients by having regular medical check-ups,” Tambuatco said.

Tambuatco added that colorectal cancer can be prevented with simple lifestyle changes such as regular exercise and avoidance of smoking and alcohol drinking.

“Ultimately, to avoid colorectal cancer an individual must eat a balanced diet with high fiber and low fat foods, Omega-3 rich foods such as fish oil, plenty of vegetables, and reduction of red meat consumption,” he said.