Stereotactic Radiation Therapy
Stereotactic [Stereo means 3-dimensional (3-D) and tactic means to probe] radiation therapy is a type of external beam radiation therapy. This treatment is extremely useful for elderly and or weak cancer patients with small, well-defined tumors. The reason is that in the elderly and or weak cancer patients, conventional surgery can be very difficult and may cause debility and in worse condition death of the patient. In stereotactic radiation therapy there is no surgical incision and loss of blood due seen in conventional surgery and our recent experience suggest that stereotactic radiation therapy may be able to replace surgery as a primary cancer treatment especially for very elderly patients who cannot withstand the trauma and blood loss of surgery.
The technique is extremely complex and needs the most sophisticated radiation machine and an expert Radiation Oncologist who has specialized in this technique. In this technique a high potent biological dose of radiation is delivered to the tumor, improving the cure rates for the tumor, in a manner previously not achievable by standard conventional radiation therapy machine. This technique is based on delivering precisely-targeted radiation in fewer high-dose treatments than the traditional therapy to the tumor only. This consequentially leads to more effective tumor kill and helps in preserving the healthy surrounding tissue.
From a technical perspective, the treatment requires a lot of planning and experience of the doctor. To start with, the tumors location is precisely mapped with CT, MRI or PET-CT. In our observations the PET-CT is of great use as it gives both anatomical and metabolic activity of the tumor and MIOs state of the art PET-CT facility meets international recommendations for the this planning. The images generated are then used to design a four-dimensional, customized treatment plan that determines beam intensity and positioning. When the treatment is for brain or CNS tumors it is called as Stereotactic radiosurgery (SRS) while for any other part it is referred to as Stereotactic radiotherapy (SRT). Both SRS and SBRT are usually performed on an outpatient basis and MIO has been in the forefront of treating medically eligible cancer patients with this technique.
- Stereotactic radiosurgery (SRS): Unlike the term surgery, the SRS treatment doesn’t involve surgery or incision (cut) to remove the cancer. SRS is mainly used to treat small brain tumors that are either malignant or benign and deep within the brain and cannot be removed by surgery because doing so would damage too much normal brain tissue. Stereotactic radiation may also be used to give an additional dose of radiation (boost) to the brain after conventional external beam radiation therapy to kill any remaining cancer cells. It is usually performed on an outpatient basis and unlike in a brain surgery process, the patients as well as their caregivers have stress free life during the treatment.
- Stereotactic radiotherapy (SRT) or Stereotactic Body Radiation Therapy (SBRT) or stereotactic ablative radiotherapy administers very high doses of radiation, using several beams of various intensities aimed at different angles to precisely target the tumor. SBRT treatments are usually given as a single dose or up to five doses once a day, although this can vary depending on the type and location of the tumor and the patient’s physical condition.
How is Stereotactic radiation therapy different from conventional therapy?
With conventional therapy, radiation is delivered in relatively small doses over the course of several weeks, with patients receiving daily treatments during that time. With Stereotactic radiation therapy, physicians are able to deliver a greater combined dose of radiation over the course of far fewer treatments. Stereotactic radiation therapy has shown dramatically better outcomes than conventional radiation therapy. Whereas two-year success rates for conventional treatment range from 30 to 40 percent, the success rates for Stereotactic radiation therapy range from 80 to 90 percent — comparable to those of resection surgery but with far fewer risks. Despite the fact that Stereotactic radiation therapy delivers higher biological dosage of radiation, patients have experienced fewer side effects, including radiation pneumonia. The most important side effect observed in our local Indian population is fatigue, especially in people with anemia for one to two week following treatment and general lethargy.
How many days do the Stereotactic radiation therapy needs to be given?
When compared to conventional therapy where low dose of radiation is given for long time of 5 to 7 weeks, in stereotactic radiation therapy depending the type of tumor (liver, brain lung etc), on the tumor location and size, the stereotactic radiation therapy may take 1day to 5 days maximum.
Has the patient to be admitted in a hospital during the stereotactic radiation therapy procedure?
The stereotactic radiation therapy treatment time takes about 20 minutes and there is no absolute need to be admitted in hospital. In fact we have observed that the patient who go and come for treatment do much better as their home environment makes them feel happy and enhances their recovery. However for outstation patients (who need to travel more than 25 kms by road) we strongly recommend hospital admission for the simple reason that the travel itself can cause undue stress and can complicate the condition.
What is the instrumentation involved in stereotactic radiation therapy:
Stereotactic radiation therapy requires specialized equipment and training, so it may not be available at all cancer treatment centers in India. MIO’s Department of Radiation Oncology faculty offer the most advanced treatments to patients whose cancers range from the relatively common to the most complex and rare in a caring, patient-focused environment. MIO is one of the first center in the area to install a new, state-of-the-art, image-guided device that provides more accurate, concentrated doses of radiation. Novalis Tx tracks the location of tumors during breathing and other movement, and delivers radiation with the highest precision. The device also shapes the radiation beam, mirroring the tumor’s size and shape. Novalis Tx is equipped with Varian’s RapidArc radiotherapy technology, delivering precise intensity-modulated radiotherapy (IMRT) up to eight times faster than other IMRT systems. Reducing the treatment time decreases the chance that patient movement will affect the treatment.
MIO’s experience with stereotactic radiation therapy:
Today at a global level, stereotactic radiation therapy is one of the most advanced techniques used in radiotherapy and is an evolving field with more sophistications being incorporated. Dr Suresh Rao the head of Radiation Oncology has specialized in this very advanced technique and at MIO many cancer patients with brain, gastric, lung and liver cancers have been treated using this technique. Our experience has been that the technique is extremely useful for treating cancer patient who are old, or cannot withstand chemotherapy or surgery. The centre has treated more than 60 cases of solid tumors of lung, brain and liver, and the therapeutic results have been very encouraging. The other important aspect is that the patient is fit in about a week’s time and able to resume their work at home or at office. The treatment and the recovery time together, is for a maximum of two weeks and this is not that strenuous on the caregivers. Additionally from cost point of view, when compared to a conventional surgery stereotactic radiation therapy is much cheaper and safer. The table here with addresses these aspects for in each of the specified cancers.