Are cancers really less aggressive in seniors?

When it comes to cancer, age plays a major role. If we know that the risk of developing cancer increases with age, an intriguing question: do cancers progress differently in older people?

Even though cancer is the leading cause of death in France, some studies suggest that certain tumors could proliferate more slowly with age. This could suggest that aging could, in certain cases, slow down their progression.

According to the National Cancer Institute (INCa), 35% of cancers detected in seniors progress slowly and require monitoring rather than immediate treatment. But what is it really? Old age and cancer form a complex duo, where biological mechanisms, the immune system and even the cell environment are aggravating factors.

Cancer: a risk that increases with age

DNA wear and tear over time

Getting older is the main risk factor for cancer. The figures are clear: according to the National Cancer Institute (INCa), around 60% of new cases of cancer concern people aged 65 and over. And this phenomenon can be explained by several biological mechanisms, including the evolution of our DNA.

Every day, our DNA is subjected to attacks: pollution, UV rays, diet, tobacco, etc. Although our body has mechanisms to repair this damage, they become less effective over time. Thus, genetic mutations accumulate in our cells and can ultimately cause deregulation. This deregulation can transform a normal cell into a cancerous cell.

A less efficient immune system

The immune system is the central element in the fight against cancer on an individual level. It detects and destroys abnormal cells before they multiply.

With age, our defenses become less effective, a phenomenon called immunosenescence. The “soldiers” of the immune system, such as T lymphocytes, useful for detecting and eliminating abnormal cells, become fewer and less efficient.

Their ability to recognize cancerous or infected cells decreases, which weakens their action. This dysfunction leaves more room for cancer cells to escape the body’s surveillance, multiply and form tumors. This phenomenon explains why cancers are more frequent and sometimes more difficult to combat in older people.

Why do some cancers seem less aggressive in seniors?

A natural slowing down of cells

Despite the increase in risk with age, the biology of cancers can change in older people. Some types of tumors seem to grow more slowly.

With age, the rate of cell division decreases. This applies to both normal cells and cancer cells. A tumor, which develops from the uncontrolled multiplication of cells, can therefore grow more slowly in an elderly person.

An “environment” less favorable to tumor growth

Cancer cells do not develop alone: ​​they need a favorable environment, rich in nutrients and oxygen. In seniors, the surrounding tissues are sometimes less able to provide these resources. Which can slow the progression of tumors.

Cancer cells do not grow alone: ​​they need essential resources such as nutrients and oxygen, provided by the blood vessels surrounding the tumor. This process, called tumor angiogenesis, is essential for the growth of a tumor. In older people, the surrounding tissues are often less dense with functional blood vessels, which limits this supply.

In practice, this means that certain tumors grow less quickly in seniors because they lack “fuel”. This phenomenon could explain why, in approximately 30% of cases of cancer diagnosed in the elderly according to INCa, tumor progression is slow and often requires simple active surveillance rather than aggressive treatment.

Tumor biology that changes with age

Cancers evolve differently depending on the age of the patient, due to biological modifications which influence the nature of the tumors. Also, some cancers evolve differently.

Cancer be you : among young women, very aggressive forms, such as “triple negative” cancers, represent approximately 15% of cases according to the National Cancer Institute. These cancers grow quickly and do not respond to hormonal treatments. On the other hand, in older women, almost 70% of tumors are hormone-dependent (estrogen or progesterone receptors), which makes them more sensitive to targeted treatments such as hormone therapy.

Prostate cancer : In older men, prostate cancer is often diagnosed at an early stage through screening. According to Santé Publique France, around 50% of prostate cancers are detected in men over 70 years old. The majority of these cancers progress slowly, and for very old or fragile patients, active monitoring (without immediate treatment) is preferred in around 30% of cases to limit unnecessary side effects.

However, not all cancers slow down with age. Tumors such as lung or pancreatic cancer remain particularly aggressive, regardless of age.

Old age and treatment: appropriate care

Even though some cancers progress less quickly, they are not without danger. In older adults, oncologists must take into account general condition, chronic diseases (such as diabetes or hypertension) and age-related frailty.

• Chemotherapy: doses are sometimes reduced to limit side effects. Targeted therapies, which directly attack cancer cells, are also favored because they are better tolerated.
• Radiotherapy: modern techniques make it possible to irradiate the tumor with great precision, while sparing healthy tissues.
• Immunotherapy: by strengthening the immune system, this approach may be an option for some seniors.

Oncologists are increasingly collaborating with geriatricians to assess patients’ ability to tolerate treatments. This assessment helps avoid overtreatment or, on the contrary, insufficient care.

NAMELY

Medical advances have enabled a clear increase in cancer cure rates, defined by the absence of relapse 5 years after treatment. Between 1990 and 2015, survival increased by 21 points for prostate cancer, 9 points for breast cancer, 12 points for colorectal cancer and 11 points for lung cancer, with variations depending on location.