Monday, November 26, 2012
ROLE OF RADIOTHERAPY IN THE MANAGEMENT OF CANCER
The post tea session began at 12.40 p.m.
Dr. Dixit went up the dais and called upon Dr. Janaki M.G. Professor and HOD; Dept. of Radiation Oncology, M.S. Ramaiah Medical College and Teaching Hospital, Bangalore to present her paper on ‘ROLE OF RADIOTHERAPY IN THE MANAGEMENT OF CANCER’
Dr. Janaki mentioned she had joined the radiation department in 1989. In the past 23 years, she had seen tremendous improvement in the quality of life among the people going through the radiation therapy. The difference was caused by the intervention of computer technology in radiation department.
Medical science has used radiation therapy for curing cancer for more a century. When Wilhelm Rontgen discovered x-rays, immediately Emil Grubbe an American physician made use of it in treating cancer. But the major contribution to the radiation came from Marie Curie, with her discovery of radioactive elements.
In earlier times, radium was used directly on the patient’s skin through a radium surface applicator. The β-rays emitted were filtered by the applicator, but the back of the applicator left the person exposed to γ rays, thus creating occupational hazards of radium therapy with for the persons working with it.
Through the pictures, Dr. Janaki showed the earlier methods of treatments and risks involved in it. Today the radio oncologist concentrates on differentiating between the tumor and normal tissue, so that the damage to the healthy tissue could be minimized.
Doctors usually recommend radiation for patients after the surgery in most cases. It is usually a part of standard cancer treatment along with surgery and chemotherapy. Usually a radio oncologist studies the case history of patient before deciding the type of radiation required for the specific condition.
The 3 different types of radio therapy approaches are:
· External radiation
· Internal radiation
· Systematic radiation
In some cases more than one type of radiation therapy is given to the patient.
During radiation therapy, there is loss of healthy tissue because radiation forms ions which are electrically charged particles in the cells through which it passes through. This process can kill cells or change genes in them preventing further growth. Unfortunately, radiation can distinguish between cancerous and non-cancerous cells. It destroys cells, irrespective of whether they are cancerous or not. In standard radiation treatment there is no way anyone can prevent damage to the normal tissue.
The major concern among the oncologists is to minimize the damage to healthy cells with accurately targeted radio therapy. In this ventures the oncologist have been helped with advancement in technology which has given them devices like linear accelerator (LINAC) which is the device most commonly used for external beam radiation treatments for patients with cancer.
The linear accelerator which delivers high-energy x-rays to the tumor is used by oncologist to treat tumors in all parts of the body as these x-ray treatments can be designed in such a way that they destroy the cancer cells while sparing the surrounding normal tissue.
A careful plan of is made by the radiation oncologist in collaboration with other experts involved in the treatment like the surgeon, radiation dosimetrist and physician. Also he is guided before and during the therapy through 3D imaging, and conventional techniques with devices like Intensity-Modulated Radiation Therapy (IMRT), Image Guided Radiation Therapy (IGRT), Stereotactic Radiosurgery (SRS) and Stereotactic Body Radio Therapy (SBRT).
CyberKnife : Cyber Knife is a non-invasive robotic radio-surgery which can remove tumors and lesions that are un-operative under normal circumstances with standard technology procedure. The oncologist is guided by the real time image guidance, to precisely target the tumor in any part of the body. The cyber-knife which is guided with technology similar to cruise missile, can deliver high dose of radiation with pinpoint accuracy.
A clinical picture of a case of cancer of Nasal Cavity which was effectively treated by cyber-knife was shown with the aid of pictures to show the astounding results.
Dr. Janaki also explained another form of radiation therapy known as Brachytherapy. It a process where the oncology surgeon implants a catheter into the cavity caused by the excision of the tumor. A part of the catheter protrudes outside the skin, which is treated by the medical professionals with antibacterial medicines to prevent infection in the area.
For radiation therapy, the end of the catheter which is protruding outside the body is connected to a remote after-loader, which sends radiation directly to the site of cancer thus reducing injury to healthy tissue.
Paper Presented by Dr. Janaki
Radiation as soon as it was discovered was used to treat cancer way back in early twentieth century. Since then lot of development has taken place in the dosimetric aspects, delivery of radiation as well as supportive care. Hence Radiation not only gives better results but also is much safer resulting in less toxicity and improved quality of life. Initially the radiation delivery was based on clinician's knowledge alone or probably with addition of fluoroscopy/x rays. With the development of CT scans, the pre treatment planning as well as on table verification during treatment has helped to focus on the target area and at the same time normal tissues included are much less.
Improved technology and incorporation of computers into treatment process has enabled precise delivery and has become important as radiation is given in fractionation and over 6-7 weeks. It's important to give the same treatment everyday for all 33 — 35 sittings. Over the last decades, advances in medical and surgical oncology along with radiation have resulted in longer lifespan of the patients and hence more of localized recurrences are seen. It's a challenge to treat the patients as they already have a compromised immune system. It is here that the advances such as stereotactic radiation, image guided Brachytherapy play a role in precisely delivering the dose only to the tumor with almost nil doses to the surrounding normal tissues.
Overall Radiation offers optimal results not only in curative setting but also for postoperative, combined chemotherapy and for palliation.