“Doctor, isn’t it true that all chemotherapy kills both the good as well as the bad cells of the body?” This is one question I am regularly asked by cancer patients, their families as well as the public.

Starting treatment against cancer is effectively going to war with the cancerous cells. “War”, to my mind, is an appropriate analogy as both are matters of life and death for those caught in the situation.

Both warfare and cancer treatment are associated with physical and psychological pain.

The common myth of chemotherapy killing both normal cells and cancer cells of the body, in particular, conjures frightful images of wanton killing of harmless civilians together with enemy soldiers through the indiscriminate unleashing of massive firepower. The battlefield is strewn with the bodies of innocent bystanders.

The scientific reality around the use of chemotherapy in the treatment of cancer is quite different.

Nonetheless, the mistaken understanding of the effects of chemotherapy on the body has caused many a patient to make the erroneous decision of declining chemotherapy when such treatment could have either offered them a cure from cancer or significantly lengthened their lives.

Take Mr T, a Malaysian Chinese in his late 50s, who unfortunately suffered from cancer of the large intestines. Fear of the purported side effects of chemotherapy led him to forgo chemotherapy as a treatment option.

On the recommendation of his friends, he skipped Western medicine and started on what he described as a “juice diet”.

He took several litres of freshly squeezed fruit juice every day as the mainstay of his anticancer therapy, firm in his belief that the antioxidant properties of the fruit juice would improve his condition of cancer.

He only began to sense that all was not well when the pain he experienced gradually increased. Equally troubling was his observation that he was losing the ability to voluntarily control his bowel movements and became incontinent, soiling himself every day.

Chemotherapy is a weapon that, to a certain extent, can differentiate cancer cells and normal cells of the body. In other words, it can tell the good guys from the bad.

Conventional chemotherapy, known as cytotoxics, differentiates the good and bad cells of the body through their relative rates of growth.

It kills cells by hitting the process through which cells duplicate their genes and divide in order to multiply. Since cancer cells multiply and grow a whole lot faster than normal cells of the body, the damage that chemotherapy does to cancer cells is substantially greater than the impact on normal cells.

Further, scientific research has revealed that cancer cells are less able to repair the damage caused by chemotherapy compared to normal cells. Hence, normal cells are more likely to heal themselves and survive the assault from chemotherapy and cancer cells are more likely to perish.

Mr T was finally persuaded by his family to seek a better solution to his condition of rapidly worsening colon cancer.

Perhaps chastised by the failed experience from his “juice diet” treatment, I found him receptive to my explanation that, on balance, the benefits of chemotherapy would substantially outweigh the potential side effects.

Mr T achieved a remission of his cancer after two months of chemotherapy.

Of course, cancer cells are not the only rapidly multiplying cells in the body. Cells in the hair roots, cells lining the inner surface of the mouth and intestines as well as the blood cells in the bone marrow, all multiply at a fairly high tempo.

Hence, chemotherapy is often associated with temporary hair-loss, mouth ulcers and diarrhoea as well as low blood cell count.

The use of conventional chemotherapy to treat cancer is akin to the use of artillery to kill enemy troops. While the artillery men do their utmost best to aim the artillery fire at the enemy troops, artillery guns, much like conventional chemotherapy, are not completely accurate and innocent civilians, much like normal cells, do get hurt as part of collateral damage.

Much of these side effects, albeit not all, can be attenuated by the careful choice of chemotherapy drugs, appropriate adjustment of the dosage as well as through the complementary use of supportive medications to neutralise some of the toxicities.

Cancer specialists designing the best treatment approach for each case of cancer are like generals directing all the weapons at their disposal to win the war against cancer.

Apart from artillery, in the form of conventional chemotherapy, scientific research has put more and newer weapons in doctors’ hands. As anti-cancer generals, they now have smart bombs, in the form of targeted therapy, to hit vital targets of the cancer enemy.

These newer types of chemotherapy exist in the form of antibodies or molecules that are able to block specific mutated genes that cancer cells make use of to drive their growth and sustain their survival.

Very often, the collateral damage to normal cells is much reduced compared with conventional chemotherapy.

Instead of just letting the white blood cells be innocent bystanders hurt by conventional chemotherapy in the fight against cancer, oncologists can now mobilise them to join in the fight against the cancer cells through the use of immunotherapy.

So you now have the answer to the question: “Isn’t it true that all chemotherapy kills both the good as well as the bad cells of the body?"

It’s not true.

Thankfully, I have found that most patients can be persuaded of this.

ABOUT THE AUTHOR:

Dr Wong Seng Weng is Medical Director and Consultant Medical Oncologist at The Cancer Centre (Singapore Medical Group) at Paragon Medical and Mt Elizabeth Novena Specialist Centre.