Runaway cancer (by Dr Wong Seng Weng)

The following article by Dr Wong Seng Weng is from Mind Your Body of the Straits Times dated 25 November 2010

Runaway cancer

When Mr L came to see me, he had advanced cancer of the large intestines, or colon cancer.
Unfortunately, the cancer had spread and invaded a substantial part of his liver.

He came across a newspaper article which cited my description of sorafenib, a new form of targeted therapy for advanced liver cancer, and requested that I gave him the treatment.
Liver cancer is entirely different from colon cancer that has spread to the liver.

Where the cancer originated from determines many of its characteristics, behaviour as well as the types of drug that would be effective against it.

No matter where the cancer cells spread to, they retain these basic characteristics determined by the mother cell from which they are derived.

That liver cancer is a different cancer from colon cancer is easily apparent to most. However, what many people, like MrL, fail to understand is that colon cancer that has spread to the liver does not become liver cancer, which evolved from liver mother cells.

Sensing that Mr L was a little confused over the difference, I used the analogy of immigration.
I explained: 'We are Asians. Even if we were to immigrate to Europe, we do not become Caucasians.

'We become Asians living in Europe. Our skin colour remains the same and we retain many of our Asian cultural and dietary habits."

'So when colon cancer spreads to the liver, the type of cell remains the same and retains the behaviour typical of colon cancer. The best treatment is to use drugs directed against colon cancer."

I selected a different form of targeted therapy for him, cetuximab, in combination with chemotherapy targeted at colon cancer with a high likelihood of inducing remission.

You, too, may have come across acquaintances telling a typical story of a patient who was first diagnosed with a particular cancer, say, breast cancer, and subsequently developed lung cancer and bone cancer.

In all likelihood, this was a story of a patient with breast cancer that spread to the lung and bones.

The discovery of cancer spread, known as metastasis, is a major catastrophe.

If we look upon cancer cells as terrorists that harm the healthy cells of our body - much like the way real-life terrorists harm ordinary citizens - then cancer cells spreading beyond the original confines of where they started are terrorists who escaped from detention.

In most cases when cancer has spread to other organs, total and permanent eradication of the disease is very difficult to achieve.

Advanced cancer, even if brought under control, tends to come back to haunt us.
War against advanced cancer becomes like guerilla warfare - a long drawn-out struggle with the cancer treatment team and the patient fighting side by side, killing most of the 'terrorists'.
But inevitably, a few survivors will successfully evade the attack to hide in mountains and caves, to regroup and fight another day.

When we have an escaped terrorist, there is no end to our troubles.

As it turned out, Mr L fared very well after treatment and the tumour in the liver shrank dramatically.

Prior to his treatment, it had been too large to be removed by surgery. But after four months of treatment, surgery could be safely performed to completely excise the tumour, removing the last vestige of the cancer in his body.

He remained in good health after a period of surveillance and, in all likelihood, has been cured. So 'the terrorist' was caught before it could do more harm.

However, it is better to stay vigilant against cancer by going for regular checks to detect it early than to have to go after a runaway cancer. We may not be lucky every time.

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Dr Wong Seng Weng, medical director of Singapore Medical Group's The Cancer Centre, has been treating cancer patients for the past 14 years. He was a Lim Boon Keng and Tan Siak Kew scholar of National University of Singapore. He concurrently holds the appointment of adjunct clinician scientist in Agency for Science, Technology and Research.

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