Radiation Therapy: Advancement in cancer care and cure

Radiotherapy is treatment of malignant or non-malignant disease using ionising radiation like Gamma rays and X rays. Since its discovery in 1895 radiation therapy has played an important role in the treatment of cancer. Radiotherapy acts by damaging DNA of tumour tissue either directly or by production of free radicals by hydrolysis of water. For last few decades technology of radiation therapy has improved immensely and radiation has become more precise and accurate. Now higher dose of radiation can be delivered more safely.
 
Radiation therapy has a wide range of uses: radical therapy (when cure is feasible with radiotherapy alone), adjuvant therapy (where it is used after surgery to sterilise a surgical site of residual tumour cell), neoadjuvant therapy (radiation used prior to surgery to reduce size of tumour and sterilize the area around and improve surgical outcome). Radiation can also be used to alleviate symptoms associated with tumours such as bleeding, pain to improve quality of life. Often chemotherapy is used concurrently with radiotherapy to make radiotherapy more effective in certain situations.
 
Types of Radiation Therapy
Radiotherapy is subcategorised in two types: external beam radiation therapy(EBRT) or teletherapy and brachytherapy. In brachytherapy radioactive small sources are placed or implanted close to or within the tumour site. EBRT involves use of radiation machine to deliver X-ray, Gamma ray, Proton or heavy ions from outside of body.
 
Common Indications of Radiotherapy
 
Radical Radiotherapy
Adjuvant Radiotherapy
Neo-adjuvant Radiotherapy
Brain Tumour
Brain Tumour
Carcinoma Oesophagus
Head and Neck malignancy
Advanced Head and neck cancer
Carcinoma Rectum
Breast Cancer
Breast Cancer
Soft tissue Sarcoma
Lung Cancer
Gastro-Intestinal Cancer
Cervical Cancer
Soft Tissue Sarcoma
Prostate Cancer
Skin Cancer
Liver Cancer
Carcinoma Anal Canal
Skin Cancer
Lymphoma
Precision and Progress
Unlike early cobalt radiation (Gamma rays) units today modern linear accelerators can produce higher energy X-rays that can penetrate more and minimise the radiation to skin. Use of beam shaping devices[Multi Leaf Collimators(MLC)] have further improved conformal radiation delivery and reduction of unnecessary dose to surrounding normal tissue. In last 2 decades side effects of radiotherapy has been substantially reduced by using a technique called Intensity Modulated Radiotherapy(IMRT). In IMRT instead of using few static beam of radiotherapy multiple actively modulated beams are utilised so that shape of distribution of radiation can be more tightly wrapped around the tumour, minimising exposure of the surrounding tissue.
 
Advancement in Imaging during Radiotherapy
Apart from conformal or precise radiation delivery system it is always important to ensure accuracy of the process of delivery. Imaging has got an immense role for accurately deliver radiotherapy. Modern day radiotherapy machines come with integrated imaging system. Imaging system may of two dimensional or three dimensional. Kilovoltage or megavoltage imaging panels are attached with the delivery system to acquire 2D(X-ray) or 3D(CT scan) images prior or at the time of radiation delivery. These technology allows radiation oncologists, physicists and technologists to have better visualisation of structures of body and as well as tumour to deliver radiation therapy more precisely than ever before. This is known as Image Guided Radiotherapy(IGRT). Researches are going on to push the limit of IGRT further by improving the quality of imaging, incorporation of MRI as IGRT tool, tracking of the tumour while in motion (like respiratory motion) will continue to enable us to target the tumour and limit radiation dose to surrounding areas.
 
Functional and metabolic imaging(eg. PET-CT scan) gives information about active(based on metabolism) parts, hypoxic areas, perfusion of tumour etc. These imaging modalities guide physicians in where they need to intensify cancer treatment.
 
Surgery vs. Radiosurgery
Due to increased precision of radiotherapy and decreased side effects one trend has been seen in last decade an increase in decision of patients to forego surgery and opt for stereotactic radiosurgery(SRS) or stereotactic ablative body radiation(SABR or SBRT). In radiosurgery or stereotactic radiotherapy high dose of radiation are targeted at small well defined tumours of brain, lung, liver and bone with goal of cure of disease with minimising exposure to surrounding healthy organs. Radiosurgery is noninvasive, better tolerated and equally effective like surgery in certain situations. But here one word of caution that radiosurgery cannot replace surgery in all cases.
 
Particle Beam Therapy
Next phase of technology that is becoming more prevalent is particle beam therapy(proton beam therapy, Carbon ion). Unlike X-rays which enters the body and exits out the other side, a proton beam can be controlled where one can decide how far those beam to enter the body. The beam has a brag peak effect by which it delivers its energy at specified depth and stops moving. One can take advantage of this kind of therapy for further reduction of normal tissue dose compared to other modalities. Proton therapy is gaining widespread use in different areas of cancer treatment and research.
 
Advancement of Radiation Therapy in India
In one aspect India closely following western world is radiotherapy technology. Apart from particle beam therapy other high end radiation technologies are available in major cities of India. But in terms of adequacy, units are far short of requirements. India is actively participating in lots of research work and multinational trials on cancer.
 
In summery
  • Radiotherapy forms part of the management of 60% of patient who are cured of cancer
  • Advances in technology mean that more patients now receive efficacious treatment with less toxicity
  • Newer technologies are increasingly available in India
  • These technologies include intensity modulated radiotherapy(IMRT); Image Guided Radiotherapy(IGRT), stereotactic radiotherapy, stereotactic ablative radiotherapy and proton beam therapy.
 
Dr Suman Mallik
MD, DNB, PDCR
Consultant – Radiotherapy

NH Westbank Health & Wellness Institute, Howrah

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