Monday 22 November, 2021

Why Haven’t We Found a Cure for Cancer?

Dudi Warsito, PhD in Oncology, is a medical writer and researcher at cancer.se.

Every year, about one in every two-to-three people is diagnosed with cancer worldwide. The number of cancer cases is expected to increase as we live longer and the world population increases. Yet, despite the billions of dollars spent on cancer research, we have yet to find a cure.

It’s important to remember that we’ve come a long way. In recent decades, enormous progress has been made in cancer research and more and more people survive cancer. In the 1980s, the 10-year survival rate was between 35-46%. Today, that figure is 69%. If you look at the figures for the two common cancers, prostate cancer and breast cancer, 88% and 86% survive after ten years, respectively, which means twice as many people survive today compared to the 1980’s.

Despite the great advances that have been made and are still being made, cancer remains complex, and it’s highly probable that we may never find one solution that cures all cancer. Dudi Warsito, PhD in Oncology and medical writer explains why.

Cancer is not a single disease

Cancer is not a single disease but over 200 different diseases that are characterized by cells dividing uncontrollably. Every cancer disease looks and behaves differently because they carry genetic differences. The large number of different kinds of cancer forms is a major contributing factor as to why there is no single cure for cancer.

An almost infinite number of mutations

Behind the more than 200 cancers, there is also an almost infinite number of possible genetic changes, so-called mutations. Each form of cancer is caused by different sets of mutations, and as the cancerous tumor grows, the cells in the tumor accumulate more mutations. This means that each tumor has its own set of mutations. A treatment that works for one person may thus be ineffective for someone else.

Not all cells in a tumor are the same

Cancer tumors are heterogeneous, that is, they are diverse in character and content, having distinct morphological and phenotypic profiles. The more a tumor grows, the more heterogeneous it becomes. A tumor consists of different types of cells, where each type carries its own set of mutations. This makes treatment much more difficult; for example, some cell types die during drug treatment while others are resistant. For the treatment to be effective, all cancer cells in the tumor must be killed.

Cancer cells are good at staying alive

Cancer cells are good at using their environment to their advantage in order to continue to grow and survive. Like normal cells, cancer cells in a tumor need nutrients and oxygen. Cancer cells can send so-called signaling molecules that tell nearby cells to form new blood vessels that transport nutrients and oxygen to the tumor through the bloodstream. They can also tell the immune system to protect cancer cells instead of attacking them.

Another example is the ability of prostate cancer cells to survive despite cancer treatment. Prostate cancer needs testosterone to grow. Men with advanced prostate cancer are usually treated with testosterone-blocking drugs. But studies have shown that when you block testosterone, the prostate cancer cells themselves begin to produce testosterone from cholesterol.

Masters at adapting

Cancer cells are under serious attack, partly by the immune system but also by various forms of cancer treatments such as chemotherapy and radiation. In order to survive the harsh environment in which they live, cancer cells need to adapt – something they’re extremely good at. By altering their own genetic material, their DNA, cancer cells can change their properties and needs for continued survival. For example, when cells in a tumor grow so much that the tumor doesn’t get enough oxygen via the blood to continue to grow, a small proportion of cells in the tumor can lower their oxygen requirements by changing their DNA, and thus continue to grow in the oxygen-poor environment. Medicines that restrict blood supply to the tumor will no longer be as effective if a few cancerous cells in the tumor can survive in an oxygen-poor environment.

Treatments stop working

The mutations that cancer cells accumulate over time mean that the cancer cells change their behavior and acquire new properties. This is a major challenge during cancer treatment as the mutations can render the treatment ineffective.

Just like antibiotic-resistant bacteria, cancer cells can develop resistance to cancer treatment. It’s not uncommon for cancer patients who initially respond well to a treatment later develop a resistance and render the treatment ineffective. If this happens, a new treatment must be started. But after a while, the cancer may again develop resistance to the new treatment. 

Will we ever find a cure for cancer?

Cancer researchers are constantly making progress. It’s likely to assume that we will probably never have a single cure for all cancers. Instead, each form of cancer must be seen as an individual disease.

It’s easy to feel hopeless when you understand the complexity of cancer and how difficult it is to win the war against cancer. But, the fact is that all the billions of dollars spent on cancer research around the world is leading to tangible results. Both survival and quality of life of people affected by cancer continue to increase. Cancer is far from being the death sentence it used to be. Thanks to all the progress, we have become better at detecting, treating, living with, and surviving cancer.

Over the years, several breakthroughs have been made in research. In 2003, the human genome was mapped. It has helped cancer researchers identify hundreds of genes linked to cancer and improve individualized treatment. Another example is immunotherapy. From being a treatment with limited potential, immunotherapy has become an increasingly common feature of advanced cancer. Learn more about three breakthroughs in cancer during the Covid-19 pandemic.

But what does the future hold? Several new diagnostic methods and treatments are being developed that will make it easier for doctors to detect and treat cancer. One hot area is nanotechnology. Today, intensive research is underway on how nanotechnology can improve cancer treatment. With the help of the new technology, it will be easier to know exactly where the cancer cells are and deliver the drug directly to the cancer, without affecting the healthy tissue. This has the potential to not only be more effective but improve the quality of life of everyone affected by cancer.

Given what we have achieved and what is currently underway, there is every reason to look to the future with hope.

Dudi Warsito, PhD in Oncology, is a medical writer and researcher at cancer.se.

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