Two examples of highly radiosensitive cancers are leukemia (cancer of the blood cells) and lymphoma (cancer of the lymphatic system). Radiation therapy is most effective when a tumor is contained, easily accessible, and located away from major organs of the body.
Head and Neck Cancers
Most cancers occurring in the head and neck region are squamous cell carcinomas, which the radiosensitivity of tumors.
Types of cancer that are treated with radiation therapy
Brachytherapy is most often used to treat cancers of the head and neck, breast, cervix, prostate, and eye. A systemic radiation therapy called radioactive iodine, or I-131, is most often used to treat certain types of thyroid cancer.
Resistance can occur when cancer cells—even a small group of cells within a tumor—contain molecular changes that make them insensitive to a particular drug before treatment even begins. Because cancer cells within the same tumor often have a variety of molecular changes, this so-called intrinsic resistance is common.
Immature (undifferentiated) hematopoietic cells that have divided (proliferated) from stem cells are highly sensitive to radiation and die due to a small amount of radiation more easily than differentiated cells.
The most radiation-sensitive organs include the hematopoietic system [4], the gastrointestinal (GI) system [5], skin [6, 7], vascular system [8, 9], reproductive system, and brain [10–12].
The nerve and muscle cells are the slowest to regenerate and are the least sensitive cells. Cells, like the human body, have a tremendous ability to repair damage. As a result, not all radiation effects are irreversible.
Breast cancer: Women with breast cancer have an overall 30% chance of recurrence. Many cases happen within five years of completing the initial treatment. Cervical cancer: Of those with invasive cervical cancer, an estimated 35% will have a recurrence.
Despite the side effects, radiotherapy can be a highly effective treatment for cancer. 4 out of every 10 cancer cures include radiotherapy as part of the treatment plan. However, radiotherapy doesn't cause cancerous tumours to shrink immediately and it can take some time for the beneficial effects to become apparent.
Some types of cancer do not respond well to radiation or chemotherapy, so a person may need to try immunotherapy. This aims to help the immune system fight cancer in the same way that it fights infections. Immunotherapies either stimulate the immune system in a general way or train it to attack cancer cells directly.
Are there side effects of the combination approach to prostate cancer radiation therapy? When it comes to early stages of disease, patients very frequently do well with either brachytherapy or external beam radiation. Success rates of around 90% or higher can be achieved with either approach.
It's typically not recommend for patients who are pregnant, who have a preexisting condition that makes them more sensitive to the side effects or who have already received high-dose radiation to that body part.
Radiation promotes the release of cytokines and growth factors through the induction of a damage response [54]. Secreted by tumor, immune, or normal cells, many of these cytokines are involved in promoting tumor cell migration, invasion, and metastasis following radiotherapy.
Radioresistant tumours are those that do not respond to radiotherapy. This group includes: osteosarcoma. fibrosarcoma.
Many of the commonly used cancer treatments, such as radiation or chemotherapy, kill tumor cells. But sometimes, after those cells have died and been cleared away, a tumor will respond by growing faster and more aggressively.
Radiation therapy remains an important component of cancer treatment with approximately 50% of all cancer patients receiving radiation therapy during their course of illness; it contributes towards 40% of curative treatment for cancer.
Which Type of Cancer Spreads the Fastest? The fastest-moving cancers are pancreatic, brain, esophageal, liver, and skin. Pancreatic cancer is one of the most dangerous types of cancer because it's fast-moving and there's no method of early detection.
Gamma rays are a radiation hazard for the entire body. They can easily penetrate barriers that can stop alpha and beta particles, such as skin and clothing. Gamma rays have so much penetrating power that several inches of a dense material like lead, or even a few feet of concrete may be required to stop them.
All these findings suggest that the radiation sensitivity, measured in terms of carcinogenic events, increases with age among adults after age of 40–45.
As such, it is very difficult to protect against gamma radiation. Because gamma radiation is ubiquitously associated with radioactive decay and it the most difficult to shield against, it is the source of most of the damage from radiation.