What Does a Radiation Therapist Do?

Tumor radiation therapy is a local treatment method using radiation to treat tumors. Radiation includes alpha, beta, and gamma rays produced by radioactive isotopes and x-rays, electron beams, proton beams, and other particle beams produced by various types of x-ray therapy machines or accelerators. About 70% of cancer patients need radiation therapy during the treatment of cancer, and about 40% of cancers can be cured with radiotherapy. The role and status of radiation therapy in tumor treatment has become increasingly prominent, and it has become one of the main methods for the treatment of malignant tumors.

Basic Information

English name

radiation therapy

Visiting department

Radiotherapy

Multiple groups

Cancer patients

Radiation Therapy

The efficacy of radiotherapy depends on radiosensitivity. Different tissues and organs and various tumor tissues have varying degrees of response after exposure. Radiosensitivity is related to the proliferation cycle and pathological grade of tumor cells, that is, proliferating cells are more sensitive than non-proliferating cells. The higher the degree of cell differentiation, the lower the radiosensitivity, and vice versa. In addition, the oxygen content of tumor cells directly affects radiosensitivity. For example, early tumors are small in size, have good blood flow, and have good effects when there are few hypoxic cells. Late tumors have large volumes, poor intratumoral blood flow, and even central necrosis. Low; local squamous cell carcinoma has better blood flow and higher sensitivity than tumors on the hips and limbs; local tumors with infection, poor blood flow (hypoxic cells), and decreased radiosensitivity. Therefore, keeping the irradiation site clean and preventing infection and necrosis is an important condition for improving the sensitivity of radiotherapy. Clinically, according to the response to different doses, the sensitivity of radiation to tumors is divided into:

Radiation-sensitive tumor

Refers to the disappearance of tumors at 20 to 40 Gy, such as lymphoid tumors, seminoma, and nephroblastoma;

2. Radiation Moderately Sensitive Tumors

Tumors that need to be irradiated 60-65Gy disappear, such as: most squamous cell carcinoma, brain tumor, breast cancer, etc .;

3. Low radiation sensitive tumor

Refers to tumors that disappear after irradiation of 70Gy, such as: most adenocarcinomas, the radiosensitivity of tumors is related to the degree of cell differentiation, the higher the degree of differentiation, the lower the radiosensitivity;

4. Radiation insensitive (resistance) tumors

Such as: fibrosarcoma, osteosarcoma, melanoma and so on.
However, some low (poor) differentiated tumors such as bone reticulosarcoma, Ewing sarcoma, fibrosarcoma, retroperitoneal and popliteal liposarcoma can still be considered radiation therapy.

Indications for radiation therapy

According to the different types of tumors in each system, the indications for current treatment can be divided into the following categories:

Digestive system

Early surgery of oral cancer has the same effect as radiation, and some parts are more suitable for radiation treatment, such as tongue root cancer and tonsil cancer. Preoperative radiotherapy is better for mid-term comprehensive treatment. Late can be used for palliative radiation therapy. Esophageal cancer is mainly operated in the early stage, and radiotherapy is mainly used in the middle and advanced stage. In addition, neck and upper thoracic esophageal cancer are generally treated with radiation because of difficult surgery and poor quality of life after surgery. Liver, pancreas, stomach, small intestine, colon, and rectal cancer are mainly treated by surgery. Colon and rectal cancer surgery may be more beneficial than radiation therapy. The efficacy of intracavitary radiation in early rectal cancer is the same as that of surgery. Radiotherapy for liver and pancreatic cancer has a certain palliative effect.

2. Respiratory system

Nasopharyngeal carcinoma is mainly radiotherapy. Maxillary sinus cancer is better before surgery. Those who can't be operated can be treated with radiotherapy alone, and some can be cured. Laryngeal cancer early radiotherapy or surgical treatment, intermediate and advanced radiotherapy, surgical comprehensive treatment. Lung cancer is mainly surgery. Radiotherapy is feasible for those who are not suitable for surgery and have no distant metastases. A few can be cured. Small cell undifferentiated lung cancer requires radiotherapy and chemotherapy.

3. Urogenital system

Clear cell renal cell carcinoma is mainly surgery, and postoperative radiotherapy has certain benefits. The bladder is mainly operated in the early stage. Radiotherapy before the mid-stage surgery has certain benefits, and palliative treatment can be done in the later stage. Renal cell carcinoma should be treated with surgery, surgery and radiotherapy and chemotherapy. Testicular tumors should be operated first, and then postoperative radiotherapy. Early surgery for cervical cancer has the same effect as radiotherapy. Radiotherapy above stage can only be used with good curative effect. Uterine body cancer is preferably radiotherapy before surgery, and those who cannot be treated can also be treated with radiation.

4. Breast cancer is mainly treated by surgery

For stage I or II breast cancer, the tumor is located in the lateral quadrant, and those with negative axillary lymph nodes are not treated with radiotherapy after surgery. Stage I and tumors are located in the median quadrant or stage II breast cancer are treated with postoperative radiotherapy. There is also benefit in pre-stage III irradiation. Radiotherapy for breast and lymphatic drainage areas after "breast-conserving surgery" for early-stage breast cancer is also effective.

5. Nervous system tumors

Most brain tumors require radiotherapy after surgery. Radiomedicine should be the predominant medulloblast. Neuroblastoma should be treated with radiotherapy or chemotherapy after surgery. Pituitary tumors can be treated with or after surgery.

6. Skin and soft tissue malignancies

The skin and mucous membranes (including the penis and lips) can be operated early or by radiotherapy, and can also be radiotherapy in the later stage; melanoma and other sarcomas should be mainly surgery. Can also be considered with radiation therapy.

7. Bone Malignant Tumor

Osteosarcoma is mainly surgery and can also be used as preoperative radiotherapy. Bone reticulum sarcoma and Ewing's tumor can be treated with radiotherapy combined with chemotherapy.

8. Lymphoid tumors

Stage and are mainly radiotherapy, and stage and are mainly chemotherapy. Local radiotherapy can be added.

Contraindications to radiation therapy

Absolute contraindications to radiation therapy are few, especially low-palliative treatments, such as analgesia for local metastases, which are mostly effective. But it also depends on the conditions of patients and units. Generally speaking, patients with advanced tumors are cachexia, which can be used as an absolute contraindication for radiation. In addition, esophageal cancer perforation and lung cancer with a large amount of effusion should also be listed as absolute contraindications.

All tumors that are not radiation sensitive should be used as relative contraindications, such as skin melanoma, gastric cancer, small intestine cancer, soft tissue sarcoma, and osteochondrosarcoma. Postoperative radiotherapy is usually added after surgical treatment.

For acute inflammation and heart failure, radiotherapy should be done after controlling the condition.

Lung cancer needs to be irradiated on a large area and should not be treated with radiotherapy when the lung function is severely incomplete.