A Way to Increase the Effectiveness of Radiotherapy Has Been Found

A muscle relaxant synthesized back in 1848 may become a modern drug against cancer. This is about the well-known medicine papaverine, which, as researchers from the Interdisciplinary Oncology Center at Ohio State University have proven, can significantly increase the effectiveness of radiation therapy by making malignant tumour cells more sensitive to ionizing radiation.

Among the effective methods of combating cancer available in modern oncology, one of the most commonly used is radiotherapy. It is based on the ability of oxygen radicals, which are formed under the influence of ionizing radiation, to destroy DNA and other important structures of the tumour cell, leading to its death. However, at insufficient levels of oxygen in the body – a condition known as hypoxia or oxygen starvation – fewer oxygen-containing radicals are produced, which in turn reduces the effectiveness of radiation therapy.

Since malignant cells divide very quickly, they require more oxygen than healthy cells. At the same time, the network of blood vessels within the tumour is poorly developed, which does not allow it to maintain an adequate level of oxygen. This leads to the fact that often cancer cells experience a lack of O2, which affects the effectiveness of radiation therapy.

Similarly, conglomerates of dead cells due to hypoxia form necrotic zones within the tumour tissue, hindering access to it for drugs introduced into the bloodstream – as a result, they simply do not reach their target. Thus, hypoxia reduces the effectiveness of not only radiation therapy but also chemotherapy.

Can Hypoxia Be Overcome?

The author of the recent study, Dr. Nicholas Denko, explains why oxygen starvation of cells is such a significant obstacle in the fight against cancer: "We know that a lack of O2 in the tissues of the tumour limits the therapeutic possibilities of radiation therapy, and this is a serious problem since more than half of cancer patients undergo radiotherapy at some stage of treatment."

"If the pathological cells that remain in the necrotic areas of the tumour mass survive after exposure to ionizing radiation," continues the doctor, "they can subsequently cause a relapse. Therefore, it is critically important for us to find a way to overcome this form of therapeutic resistance."

In search of a solution to the problem of low effectiveness of radiation therapy, Dr. Denko and his team stumbled upon a drug called papaverine. Nowadays, it is widely used, but has never been used in cancer patients. Papaverine is usually prescribed to combat muscle spasms and sexual dysfunction.

The action of the drug consists of suppressing the respiratory process in mitochondria, tiny organelles that are called the energy stations of the cell. The group of researchers led by Dr. Denko discovered that by blocking the active consumption of oxygen by the mitochondria, it is possible to increase the sensitivity of the tumour to ionizing radiation. They proved that taking a small dose of papaverine before the start of irradiation reduces mitochondrial activity, thereby combating oxygen starvation and helping to destroy cancer cells.

Previous attempts to solve this problem focused on increasing the level of oxygen in the tumour cells. The new study offers a radically different approach based on reducing the consumption of O2 by the cells. Importantly, the sensitivity of healthy tissues to radiation therapy remains unchanged after the use of papaverine.

What’s Next?

The results of the study were published in the leading American scientific journal Proceedings of the National Academy of Sciences. In a detailed commentary on the publication, the scientists noted: "The fact that cells with a lack of oxygen are two to three times more resistant to radiation therapy than cells that do not experience oxygen starvation is a well-known and proven fact. Our study may become an important milestone in the decades-long attempts by scientists to find a way to cope with hypoxia, which is the main reason for the low effectiveness of radiation treatment."

However, this discovery is not the end of the matter. Researchers hope that by altering the structure of papaverine, they will be able to enhance its action in the future. By updating its component composition, they could also potentially reduce the side effects of the drug.

Despite the fact that it will take considerable effort and a series of trials before the new approach is widely applied, the results of the American scientists' research look promising. Especially since their proposed method is remarkably simple – to use a well-known and proven drug to enhance the effectiveness of already existing cancer treatment methods.