Cancer on my mind

AS a doctor, I am interested in how the human mind works. As an oncologist, I am interested in the lure of alternative medicine. And so I have tried to understand why, in spite of all the scientific evidence at hand, there are many amongst us who do not want to undergo conventional cancer treatment – surgery, radiotherapy, chemotherapy and targeted therapy – but instead risk being treated by unproven and potentially dangerous alternative therapies.

I am sure the lack of science education plays a role. Science is more than the description of plants and animals. It is more than technology and engineering. To understand science is to understand the principles, methodologies and philosophy of science.
But I feel there is more than just this particular deficiency in our educational system.

It may also be due to something called the confirmation bias. This is a well-studied phenomenon in cognitive science, which is the science of how the mind works. We notice the hits and ignore the misses in support of our favourite beliefs. Say we have a strong bias against chemotherapy (which may cause vomiting, hair loss, loss of appetite, etc). We tend to either ignore stories of chemotherapy curing cancer or conveniently forget them.

On the other hand, we will repeatedly tell the story of the patient who felt better after taking a herb and forget the times herbs did not work.

A local Malaysian flavour of the confirmation bias is called selective hearing impairment. Many wives tell how their husbands never hear reminders to visit their mothers-in-law, but will always remember to watch the important football matches of the English Premier League!

This brings us to the matter of evidence (“proof” if you prefer) in clinical practice. Firstly, the anecdote. An anecdote is a story of something happening to someone in a certain way at a certain time.

Another word for it in medicine is the case history. A cancer patient gets better after taking an herbal drink (“the more distasteful it is, the more potent it will be”) and we are impressed. We tell this story to many of our friends and soon this herbal drink becomes the cure for cancer (for the month at least!).

Ask any doctor. Or for that matter, ask any intelligent medical student. Anecdotal evidence is the weakest level of evidence. In short, it is never to be used at all to prescribe treatment. There are in fact four higher (“stronger” if you like) levels of evidence. The highest level and the one doctors rely on is the randomised clinical trial (R.C.T.).

We are all unique. What works in one person may not work in another. What works in a subset of patients with a certain disease may not work in another. The first step in a R.C.T. is to select the group of patients we want to test a certain treatment on.

I give an example. Early colorectal cancer is treated by surgery. The cancer has not (apparently) spread to other parts of the body, based on x-rays and other imaging examinations. But the cancer will recur in a significant proportion of patients.

We want to know if by adding a new drug, oxaliplatin, there will be fewer patients who suffer a recurrence.

We randomly assign over a thousand patients to the conventional two drugs treatment (5-FU And Leucovorin) and a thousand more to the new three drugs combination (oxaliplatin, 5-FU and Leucovorin).

We carry out very complicated statistical calculations on how these two groups of patients will fare in the coming years.

Finally we reach the conclusion that the three-drug combination cures more patients.

Thousands of clinical trials are done in a similar way to test hundreds of drugs in scores of clinical scenarios. This is all very laborious and expensive. But what choice do we have?

The answer is – none at all.

The R.C.T., however complicated and tortuous it may seem to many people, is the only way to prove a treatment works. Trials like these generate new treatment regimes that cure more and more cancer patients every year.

Our subjective biases are no substitute for objective research when it comes to treating cancer.

Note: Dr Albert Lim Kok Hooi is a consultant oncologist. For further information, e-mail starhealth@thestar.com.my. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
source:thestar.com.my