Leukemias and lymphomas, while exceedingly radiosensitive, are not readily radiocurable.
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.
Glioblastoma brain cancer is one of the types of cancer rarely associated with radiation exposure.
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.
Many cancer patients who are treated with chemotherapy and/or radiotherapy eventually become resistant, and acquired resistance accounts for the majority of cases.
Your doctor may then suggest a second-line treatment, also called second-line therapy. It is a different treatment that is likely to be effective. Depending on the type of cancer you have and the available drugs, you may be able to have third-line therapy or additional rounds of treatment after that.
Radioresistance in cancer is often caused by the repair response to radiation‐induced DNA damage, cell cycle dysregulation, cancer stem cells (CSCs) resilience, and epithelial‐mesenchymal transition (EMT).
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.
Embryonal tumors, as well as tumors composed of rapidly growing cells, are sensitive to radiotherapy. Lymphoid cells are particularly susceptible to radiation. On the contrary, neurosarcoma, glioma and melanoma are radioresistant.
This is usually temporary, but if someone's energy reserve is very low, it's hard to bounce back. There are times when radiation will not cause local damage, as levels are still below the lifetime amount, but the person is too weak to tolerate more treatments. This is a difficult assessment.
Not all types of radiation have been proven to cause cancer. Learn what we know about exposure to lower-energy forms of radiation and cancer risk.
Although there are no curable cancers, melanoma, Hodgkin lymphoma, and breast, prostate, testicular, cervical, and thyroid cancer have some of the highest 5-year relative survival rates.
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.
If radiotherapy doesn't kill all of the cancer cells, they will regrow at some point in the future. We have more information about radiotherapy treatment. Some immunotherapies or targeted cancer drugs may get rid of a cancer completely. Others may shrink the cancer or control it for some months or years.
Radiation therapy is always a balance between destroying the cancer cells and minimizing damage to the normal cells. Radiation doesn't always kill cancer cells or normal cells right away. It might take days or even weeks of treatment for cells to start dying, and they may keep dying off for months after treatment ends.
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].
Lung and esophageal cancer are one of the common cancers after breast irradiation.
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.
Certain extremophiles, such as the bacteria Deinococcus radiodurans and the tardigrades, can withstand large doses of ionizing radiation on the order of 5,000 Gy.
Lung. Many studies have shown that the lung ranks among the organs that are most resistant to LDR damage.
The bacterium Deinococcus radiodurans is a champion of extreme radiation resistance that is accounted for by a highly efficient protection against proteome, but not genome, damage.
Cells in late G2 and mitosis (M-phase) are the most sensitive to radiation, and cells in late synthesis (S-phase) are the most resistant (Fig. 23.10).