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Types of Radiotherapy Treatment

  1. Radical radiotherapy:
    1. Radical radiotherapy is used in early stages of cancers at an aim to cure.
    2. The radiation oncologist takes a lot of time to accurately delineate the tumor volume, analyze image data, simulate, perform dosimetric analysis of a plan and actual radiation dose delivery. It usually takes about 6-8 weeks to complete a course in multiple sequential phases called shrinking field technique.Q
    3. The common tumors treated by radical radiotherapy are vocal cord cancer of larynx, nasopharynx, cancer of uterine cervix, skin cancers, bladder cancers, breast cancers, and prostate cancers etc.
    4. Radical radiotherapy involve multiple hospital visits, prolonged course of treatment up to normal viscera tolerance, expect and accept some degree of acute and chronic side effects.
Radical Radiotherapy Should Be Considered In Patients With Localized Lung Cancer If Surgery Is Contraindicated Or Refused. It Is Suitable For Less Than 5% Of Patients. Criteria For Eligibility Are As Follows:
  1. Tumors 5 Cm Or Less In Maximum Dimension
  2. Age Less Than 70 Years
  3. Good General Medical Condition
  4. Adequate Pulmonary Function
  5. Non-Small Cell Histology
  1. Adjuvant radiotherapy
    1. The word adjuvant is derived from the Latin verb called ‘adjuvere’ meaning to help. In situation where radiotherapy is utilized for the improvement of results of another modality (usually surgery) is called adjuvant radiotherapy.
    2. Radiotherapy can be delivered before surgery (preoperative radiotherapy), after surgery (postoperative radiotherapy), during surgery (intraoperative radiotherapy and combination of preoperative and postoperative radiotherapy (sandwich radiotherapy). Q
    3. Ultimately survival.
    4. The commonly encountered cancers requiring adjuvant radiotherapy are rectal cancers, head and neck cancers, breast cancers, and brain tumors etc. Radiotherapy is however, most frequently used in postoperative set up.
    5. The brightest example of postoperative radiotherapy is demonstrated in stage-I seminoma of the testis. By giving prophylactic postoperative radiotherapy, the relapse reduces from 15% to near zero percent. Q
    6. The other example is in post excision breast cancer. In this situation the breast relapse reduces from 35% to less than 10% after postoperative radiotherapy.
  2. Chemoradiotherapy
    Sometimes anti-neoplastic drugs like cisplatinum, 5FU and hydroxureaQ when given in conjunction with radiotherapy, enhance the efficacy of radiation. When radiation given concurrently with chemotherapy the cancer cell kill increases by two fold. These principles are used in the organ preservation techniques in anal canal cancer, bladder cancer, esophageal cancer and cervical cancers.
  3. Multi-modal (holistic) approach.
    1. Due to volume effect of the tumor and proportion of cancer cells removed at a time, many anticancer treatments are joined together to attack cancer cell in many ways called multi-modal (holistic) approach in cancer treatment.
    2. If such tumor were removed totally by surgery, the remaining tumor load would be only 109, which may not be visible (microscopic).Q
    3. Radiation therapy if given to that area can reduce that tumor burden to 106 or below. In this low tumor cell load, they can be easily controlled by hosts own immune defense or immunotherapy. Chemotherapy can also decrease proportional amount of cell burden in chemosensitive tumor alike radiotherapy.
    4. In a combined modality policy, radiotherapy and surgery interval should be kept between 4 to 6 weeks except for Wilms' tumor where radiotherapy should be started on 10th day. Q If the interval is prolonged beyond stipulated period, resistant clonogens grows and make the tumor more difficult to control by radiotherapy.
    5. The best example of combined modality therapy in cancer is in the management of Wilms’ tumor. The above tumors are managed with initial nephrectomy then local radiotherapy (10.8 Gy) on the 10th day and subsequently chemotherapy (VAC) for 12- 24 months.
    6. The other examples are management of:Q
      1. locally advanced breast cancer,
      2. cancer endometrium, and
      3. soft tissue sarcoma.

Note: Indications for post-operative radiotherapy in a case of carcinoma endometrium include Myometrial invasion of more than half thickness, Positive lymph nodes, and Endocervical involvement.Q

  1. Intraoperative radiotherapy [IORT]
    This is a very simple technique where radiation from a deep x-ray machine or electron beam from a dedicated linear accelerator is delivered to the tumor bed after the removal of the tumor. This procedure is done under the supervision of radiation oncologist. The tumor bed is considered to harbour microscopic or gross residual tumor cell seedlings, which are difficult to control, by external beam radiotherapy.
    This is most required in the abdominopelvic sites. QFollowing surgical excision of the abdominal tumor, a single large dose of radiation (usually 20 Gy) is delivered to the precise area under observation by an electron applicator. IORT seem to improve local control figures in retroperitonel soft-tissue sarcomas, pancreatic cancers, and other abdominopelvic tumorsQ where external radiation is not feasible in view of higher normal tissue complications.
  2. Intensity modulated radiotherapy (IMRT)
    Now a days it is possible to modulate a given radiation beam accurately, which can fit to the tumor shape. Modern linear accelerators are attached with multi-leaf collimator to alter the quality of radiation beam and to modify dose distribution. IMRT found useful in the treatment of small brain tumors, and head and neck cancers. It is best suitable for carcinoma of prostate.Q
  3. Stereotactic Radiosurgery
    It is a high precision, stereotactically guided delivery of large dose of radiation in a single fraction. It can be delivered with the ‘gamma knife’  consisting of multiple cobalt-60 radioactive sources or X-rays from linear accelerator.
    It is used for treating following lesions:
    Solitary cerebral metastasis
    1. Arteriovenous malformation
    2. Small meningiomas
    3. Schwannomas
    4. Pituitary adenomas
    5. For brain tumors this type of radiotherapy ,does not use a knife , but very precisely targeted beams of gamma radiotherapy from hundreds of different angles. Only one session of radiotherapy, taking about four to five hours, is needed.
    6. For this treatment a specially made metal frame is attached to patient’s head. Then several scans and x-rays are carried out to find the precise area where the treatment is needed.
    7. During the radiotherapy, patient lie with head in a large helmet, which has hundreds of holes in it to allow the radiotherapy beams through.
    8. This treatment is available only in specialist hospitals and is not suitable for all patients with brain tumors.
Special situations:
Neoplastic Spinal Cord Compression: Treatment
Management of cord compression includes glucocorticoids to reduce cord edema, local radiotherapy (initiated as early as possible) to the symptomatic lesion, and specific therapy for the underlying tumor type. Glucocorticoids (dexamethasone, up to 40 mg daily) can be administered before the imaging study if the clinical suspicion is strong and continued at a lower dose until radiotherapy (generally 3000 cGy administered in 15 daily fractions) is completed. Radiotherapy appears to be as effective as surgery, even for most classically radioresistant metastases.

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