RADIOTHERAPY

21.03.2024

RADIOTHERAPY IN CANCER TREATMENT

Radiotherapy is a widely used method in cancer treatment. This treatment uses high doses of radiation to destroy cancer cells or slow their growth. Radiotherapy delivers radiation directly or closely to targeted cancer cells, which damages the cells' DNA, preventing or reducing their ability to multiply. Radiotherapy can be used as the primary treatment method in cancer treatment, or it can be used to shrink or destroy cancer tissue before or after surgery. It is also preferred as a palliative treatment in some cases to reduce pain and control the spread of cancer. Modern radiotherapy methods utilize advanced imaging and radiation directing techniques to minimize damage to surrounding tissues while increasing the effectiveness of treatment. In this way, patient comfort and safety are increased during treatment.

Image 1: Radiotherapy is known as radiation therapy. High-energy X-rays are delivered to tumor tissues and the proliferation of cancer cells is prevented.

MECHANISM OF ACTION

Radiotherapy works by damaging the DNA of cancer cells. This damage is caused by energy created through photons or charged particles. DNA damage occurs in two ways: direct and indirect. Indirect damage results from DNA damage caused by free radicals, especially hydroxyl radicals, resulting from the ionization of water. In photon therapy, the effect of radiation occurs mostly through free radicals. Double-strand DNA breaks lead to the death or slowdown of cells because such damage is more difficult to repair.​

The details of this process can be explained as follows:

Damage to DNA: Radiotherapy works by directly damaging DNA, the genetic material of cancer cells. High-energy radiation causes breaks in DNA strands. These breaks prevent the cell from dividing and multiplying.

Causing Cell Death: Cancer cells whose DNA is damaged usually cannot be repaired and eventually die through apoptosis (programmed cell death) or necrosis (cell death).

Cell Cycle Arrest:Radiation stops the cell cycle, preventing cells from dividing and multiplying. This is especially effective for rapidly dividing cancer cells.

Oxygen Effect: The effectiveness of radiotherapy depends on the oxygen level in the target tissue. In high oxygen environments, the damage caused by radiation to cancer cells is greater. For this reason, oxygen therapy can sometimes be used together with radiotherapy.

Cancer Tissue Specificity: Modern radiotherapy techniques focus radiation on cancer cells as much as possible to cause minimal damage to healthy tissues. For example, methods such as IMRT (Intensity Modulated Radiation Therapy) and proton therapy optimize the distribution of radiation.

Repeat Dosing:Treatment is usually administered in small doses over several weeks. It allows cancer cells to sustain continued damage while providing time for healthy cells to repair damage from radiation.

Combination Treatments: Radiotherapy is often used in combination with surgery or chemotherapy. This combination increases the effectiveness of treatment by targeting cancer cells in various ways.

These mechanisms of action of radiotherapy make it an important option in the treatment of many types of cancer. The treatment plan for each patient is customized based on the type and stage of cancer, the patient's overall health, and other factors.

Image 2: In order to prevent damage to healthy surrounding tissues during radiation treatment, a drawing is made on the area to be irradiated before the treatment.

TYPES OF RADIOTHERAPY

Radiotherapy methods include various techniques used in cancer treatment. These methods are selected according to the type of cancer and the patient's condition. Here are some common radiotherapy methods:

External Beam Radiation Therapy (EBRT): In this method, high-energy rays aimed at cancer cells are sent from outside the patient's body.

Brachytherapy: In this treatment, radioactive materials are placed directly into the cancerous tissue. This is often used for prostate, cervical, breast, and some head and neck cancers.

Intraoperative Radiotherapy:This technique is radiation applied directly to the tumor during surgery. It specifically targets remaining cancer cells in the area where the tumor was removed.

Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiotherapy (SBRT): These methods precisely focus very small, high doses of radiation on the exact location of the tumor. SRS is usually used for brain tumors, while SBRT is used for tumors in other parts of the body.

Proton Therapy:Proton therapy uses proton beams to damage cancer cells. This treatment reduces the risk of damage to surrounding tissues and is used especially in children and for tumors near sensitive organs.

Each radiotherapy method is determined by the type of cancer, its location, and the patient's general health condition. Treatment options and approaches are constantly evolving and the most appropriate treatment plan for each patient is carefully prepared by the treatment team.

IN WHICH CANCERS IS IT EFFECTIVE?

Radiotherapy is an effective method in the treatment of many types of cancer. However, while some types of cancer are more sensitive to radiation, it may not be effective for others. Here are the types of cancer for which radiotherapy is generally effective and the conditions in which it may be ineffective:

Types of cancer for which radiotherapy is more effective

Head and Neck Cancers: Radiotherapy is often used to treat various types of cancer in the head and neck area.

Breast Cancer: In both early and advanced stage breast cancers, radiotherapy can be applied after surgery or together with other treatments.

Cervix Cancer: Radiotherapy has an important role in the treatment of cervical cancer.

Prostate cancer: Radiotherapy is a common treatment option, especially in early stage prostate cancer.

Eye Cancers: Some eye cancers can be successfully treated with radiotherapy.

Types of Cancer for which Radiotherapy is Less Effective

Radiotherapy may not be effective for some types of cancer. This depends on the type, biological characteristics and stage of the cancer. Generally, the types of cancer for which radiotherapy is less effective or ineffective include:

Renal Cell Carcinoma (Kidney Cancer): Generally less sensitive to radiotherapy.

Hepatocellular Carcinoma (Liver Cancer): Liver cancers may be resistant to radiotherapy.

Pancreatic cancer: Pancreatic cancer is generally less sensitive to radiotherapy and is usually treated with surgery and chemotherapy.

Melanoma: Melanoma may show variable sensitivity to radiotherapy and other treatment methods are generally preferred.

Some Brain Tumors: Some, but not all, brain tumors may be less sensitive to radiotherapy.

For these types of cancer for which radiotherapy is not effective, other treatment methods are generally preferred. Choosing the most appropriate method of cancer treatment may vary depending on the type of cancer, its stage and the general health status of the patient. This information is a general guide and a medical professional should be consulted for specific treatment plans.

Image 3: Radiotherapy treats the tumor by making targeted regional shots with advanced technology devices.

SIDE EFFECTS

The severity and duration of these side effects may vary depending on the dose of radiation administered and the area treated. Each patient's experience may be different, and management of side effects varies depending on individual health status.

Side effects of radiotherapy are as follows:

Skin Problems:Redness, itching, blistering, or peeling may occur.

Tiredness:Widespread fatigue may occur during treatment.

Head and Neck Area Problems: Mouth sores, dryness and difficulty swallowing may occur.

Chest Area Treatments: Cough, shortness of breath and difficulty swallowing may occur.

Abdominal Area Treatments: Nausea, vomiting, diarrhea or constipation may occur.

Pelvic (Lower Abdominal) Area Treatments: Difficulty urinating or sexual dysfunction may occur.

General Side Effects: Hair loss or changes in blood values ​​may be detected.

Radiotherapy side effects are usually temporary and improve after treatment ends. Management of radiotherapy side effects may vary depending on the patient's condition and the severity of side effects. Special creams or lotions can be used to alleviate side effects, such as skin irritation. Gastrointestinal side effects such as nausea and vomiting can be controlled with antiemetic drugs. Doctors usually give recommendations for problems such as burning during urination. Effective management of side effects during treatment can help the patient take full advantage of radiotherapy. Therefore, it is important to treat side effects that occur during radiotherapy and increase patient comfort.

Resources:

https://www.cancer.gov/about-cancer/treatment/types/radiation-therapy

https://en.wikipedia.org/wiki/Radiation_therapy

https://www.mayoclinic.org/tests-procedures/radiation-therapy/about/pac-20385162

https://www.cancer.gov/about-cancer/treatment/types/radiation-therapy

https://www.cancer.org/cancer/managing-cancer/treatment-types/radiation/basics.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3298009/