Colon cancer

In 1976...

Compared to today, what was known about colon cancer in 1976 is almost as stark as the contrast between night and day. “Given what we know now, I’d say our knowledge in the 1970s was relatively primitive, as were our treatments,” said Dr. Malcolm Moore, head of medical oncology at Toronto’s Princess Margaret Hospital.

The story of screening, diagnosis, treatment and survival then and now is quite different. Thirty years ago, screening was just beginning to be considered as a way to catch the disease early. It was not commonly done, and the prevailing technique combined a barium enema with an x-ray. Barium is a chalky liquid that shows up on x-rays and helps to show what internal anatomy looks like.

Largely due to the lack of screening, most cases of colon cancer were caught at advanced stages. And as with any disease, the earlier its caught and treatment begun, the better. Treatment in the 1970s consisted of a drug called 5FU, but “that was basically it,” Dr. Moore said.

Today…

In the early 21st century, the outlook for colon cancer is more promising. Survival has improved significantly. “In the 1970s, the 5-year survival for stage 3 cancer was around 40% to 45%. Now, it’s around 60% to 65%. For stage 4 (advanced metastatic disease), a patent would probably live an average of 6 to 9 months – now it’s around 24 months,” Dr. Moore said. Survival rates have risen largely due to an increase in the number of people who are screened for the disease and new drug advances.

For screening, colonoscopies (use of a hose-like tube with a camera attached to the tip, which is inserted internally) provide clear images that show whether colon tissue is healthy or diseased. With screening, the disease is caught earlier.

Early treatment improves the likelihood of a cure. Nowadays, more treatments are available, rather than 5FU alone. People are given medications that are most effective for their specific cancer, and there is a better understanding of when to use the drugs. Now, “we give chemotherapy after surgery, for people whose cancer has been removed or are at risk of it coming back. We can lower the risk of the cancer coming back,” Dr. Moore said. Understanding the timing of chemotherapy is an important advance. In fact, this one change has led to about a 15% increase in cure rates after surgery.

New types of drugs, such as biological or targeted therapy, are now being used. They work differently than chemotherapy – by slowing or preventing tumour growth. They are often combined with chemotherapy.

Tomorrow…

Genetics research is shedding more light on colon cancer. It has revealed that colon cancer is actually a spectrum of diseases. This information is being used to figure out which treatments work best for specific versions of the disease, but a lot of work still needs to be done.