Cancer is not one disease

By Dr ALBERT LIM KOK HOOI

You have to understand that cancer is not one single entity, and neither are heart disease, hepatitis, arthritis or any other disease-complex.

IF I had to pick one lesson to teach about cancer and its treatment, it is this: cancer is not one disease. It is perhaps a hundred different diseases.

Because cancers are so different from each other, cancer patients can be divided into approximately 100 groups. This calls for a hundred different treatment approaches.

Take just one of these 100 groups. Advanced or metastatic breast cancer is common. It is more common in Malaysia than in the developed world. Patients here often present to the doctor late either because of ignorance or shame. There are also patients who originally present with early disease but who refuse chemotherapy and hormonal therapy after their breast surgery. Their cancer then recurs and spreads.

Advanced breast cancer can be divided into four subsets as a first approximation. The division is based on two molecular characteristics of the tumour: HER2 and ER. Both HER2 and ER are receptors or docking sites on the surface of the cancer cell which predict which cancer drug will work. HER2 and ER can be either positive or negative. Two variables each of which there can be two possibilities make four groups.

We now have four groups of patients with advanced breast cancer viz. i) HER2 positive ER positive, ii) HER2 positive ER negative, iii) HER2 negative ER positive, iv) HER2 negative ER negative. We approach each of the four groups differently. We use anti-HER2 treatment for the two HER2 positive groups. We use hormonal treatment for the two ER positive groups. In addition, we use chemotherapy for all four groups at some time during their illness.

Actually, advanced breast cancer (or any cancer) is more complicated than that. Not only are the four groups I spoke about important, we oncologists also take into account the tumour burden (how much cancer there is in the body) as well as the status of the patient’s internal organs. How well are her heart, bone marrow, liver and kidney functioning? All this will influence the treatment we prescribe.

Patients often (or is it always?) compare notes and wonder why their treatments differ even though they both have the “same” cancer. I hope there is less need to wonder after reading this article. Some patients demand the oral treatment their fellow sufferers are on because it is more convenient than injections.

They want the chemotherapy that does not cause hair loss. Sure, we can give convenient, tolerable treatment to them but it may not be the appropriate and effective one for their cancer.

Some cancer patients die within a few weeks of diagnosis. Many patients are cured and survive decades after cancer treatment. They lead meaningful, comfortable lives. Between the first and second scenario, everything else is possible. There is much variability even within each subset of cancer patients, let alone the whole cohort of cancer patients.

Once again, let me dispel the misconception that cancer is one disease that requires one therapeutic approach. It is not. It is a 100 different diseases with 100 different treatment approaches. Ozone therapy, Gerson therapy, cytotron therapy, herbal therapy and qi gong for cancer imply that cancer is one disease. Even if these alternative and complementary therapies are not meant to treat the cancer directly but to boost the immune system and palliate, it still does not make sense.

The immune system is a very complicated and heterogeneous system that is not so easily boosted. Palliative medicine has come a long way and is as much on a scientific footing as oncology. Similarly patients who need palliative care can be divided into 100 groups which required 100 different approaches.

The more we know about cancer, the more we find the need to split cancer patients into more and more groups. It is a generalist’s nightmare and a reductionist’s dream.

I hope other medical specialists will cheer me on. Heart disease is not one disease. Neither is arthritis, diabetes, stroke, hepatitis or tuberculosis.

My colleagues also dissect the disease complex of their speciality into smaller entities and treat each one differently.

They are also faced with patients who tend to “lump” (rather then “split”) and to compare notes. Cultural beliefs have engendered myths and legends about how the human body works, how it goes wrong and how good health can be restored.

Moreover our educational system may not have adequately prepared us to understand contemporary science-based and evidence-based medicine.

Not only should science and mathematics be taught in English, perhaps science and mathematics should also be taught in science and mathematics.

- THE STAR