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The modern linear accelerator has not only decreased skin toxicity but also gave a way to treat tumours that are situated deep in the body.
With public hygiene and modern medicine having some success in eradicating or at least controlling most of the killer infectious diseases that used to be the bane of human society, focus is now back on the emperor of all maladies, cancer.
In the last few decades, medicine declared a war on this terror and modern technology is often in the forefront, increasingly assisting what was once deemed a pure biological stream. From improved diagnostic techniques to delivery of drugs and from searching for etiologies to improvement in rehabilitation, there is no single facet of oncology that is not affected by technology. And yet the branch of oncology that has seen most advances with improvements in engineering has been the field of radiation oncology, helped by the fact that it was always seen as a specialty where physics was married to biology. Despite all the awe that the new tools of radiation oncology generates in her sister specialties, it is still one of the most misunderstood medical specialty among the general public. Often, the term radiation evokes the image of a nuclear bomb, a cancer causing agent and mostly with palliation of pain for patients where no cure is in the offing.
This exciting science of radiation oncology had rather fortuitous origins on a Friday afternoon, on November 8, 1895 to be precise, in the lab of Dr. William Conrad Roentgen, a 50-year-old professor of theoretical physics at the University of Warsburg. He was working on a primitive Hittorf-Crookes tube and producing cathode rays when he noticed some black lines across the platinocyanide screen lying on a nearby bench. He knew that these could not be due to the cathode rays. He repeated his findings and presented them to the Physical and Medical society of Warsburg on December 28, 1896. There were others who might have discovered X-rays before Roentgen. William Crookes while working on cathode rays noticed the fogging of photographic plates and returned the plates to the manufacturer complaining they were damaged. Philipp Lenard, a nobel laureate himself, compared the role of Roentgen to that of a midwife who was present at the time of the birth of X-rays, claiming that he was the ‘mother of X-rays. But Roentgen, like many other illustrious predecessors, Isaac Newton or Alexander Fleming had the inquisitive mind to ask the crucial question, why? Medicine will always be indebted to this gentle physicist. Within an year of the discovery of X-ray there were reports of using it to treat a wide variety of cancers. Dr. Emil Herman Grubbe, Dr. Leonhard Thaddeus Voigt, Dr. Victor Despeignes and Dr. Leopold Freund all reported cases where radiation was used for the treatment of cancers. In a story often resembling that of Roentgen, in 1896, Henri Becquerel discovered radioactivity and Alexander Graham Bell, who discovered the telephone, suggested the use of radium for deep seated tumours.
In earlier years, the biggest problem faced while treating cancers with radiation was the high chances of skin reactions due to the lesser energy of beams. The modern linear accelerator with its megavoltage energy has not only decreased skin toxicity but also gave a way to treat tumours that are situated deep in the body, often inaccessible to surgery. The extensive use of computers and mathematical algorithms in planning radiation is now helping the radiation oncologist to deliver high dose to the tumours and decreasing the normal tissue doses. All great powers come with great responsibility and more and more emphasis is now placed on the accuracy of delivery as the margin for error is extremely low in modern technology. Intensity modulation and image guidance are now routine practices for many tumours. Methods to track tumours that are moving and treat them during certain phases of respiration are now available. Also, going beyond X-rays, particle beams like protons are waiting in the wings. There is also an evolution in the thinking of a modern oncologist. Once curing the disease was the sole interest of an oncologist, while leaving primum non nocere to lesser mortals, now there is an increased emphasis on decreasing normal tissue toxicity and improving the quality of life.
There is also a flip side to modern technology. Often technology is moving at a pace beyond the needs of clinical requirement. There is a mismatch in access to technology with almost all modern machines located in private setups and major cities. Selecting the right technique for the right patient, moving towards lesser number of radiations and using linear accelerator platforms that are capable of a wide variety of functions, from palliative to high precision treatment rather than exclusive machines which deliver only certain treatment, will help in reducing the cost for the society.
The fight between high precision targeted radiotherapy and cancer is often deemed as an unstoppable force meeting an immovable object. And yet, in this battle of attrition we are daily moving ahead losing some every day, but saving many more.
Dr. Arunlal M.is Consultant, Radiation Oncology, Aster Medcity, Kochi
