Breathing with the tumor , Advances in cancer care

Mrs. Sharma, aged 77 years presented with few months back developed severe headache, intermittent fever, pain all over the body and dry cough. Investigations led to the diagnosis of malaria which was a great relief for her. But during the investigations in addition to certain benign findings in addition to the changes in the brain indicative of blood supply problems (ischaemia) a small mass in the left lung. The size of the mass was less than 2cms. A CT guided Biopsy was done revealed cancer of the lung. In medical terminology it was very early stage of lung cancer, in this situation diagnosed accidentally when investigating for other problem. Is it a blessing in disguise? Just a few years back it would not have been a blessing. The only choice for this stage at that time was only surgery and many times surgery was not possible in this situation because of relatively advanced age & associated diseases like that of heart. There goes up in smoke the slogan “cancer is curable if detected early”. Additionally, in such an age, surgery did carry a risk of mortality. A few years back a new technique of radiotherapy was designed. That is stereotactic body radiotherapy, in short SBRT. Stereotaxy means ability to locate a point in the body in three-dimensional space. If that is attained, then one could deliver relatively high dose of radiation to the tumour avoiding the normal tissue attaining the same result that of surgery. Theoretical foundation was laid, later came the implementation. The first problem was tackling the movement of tumor in the lung. It was realized early that the tumor moves as much as 4 cms during the breathing, not only up and down but in all directions. The way out was to treat the volume encompassing all the positions of the tumour. This was done by including 1 to 2 cms of normal lung tissues around the tumor and dose of radiation was kept a level that could be tolerated by normal tissues with acceptable side effects. Tumor control rates were encouraging but were not significant. With what is known as 4Dimension CT scan tumor movement can be mapped. And radiation was directed to the tumor when it came with in specific phase of breathing cycle, usually in late expiration and beginning of inspiration phase. The other variation in technique was to make the patient hold her/his breath in particular phase of breathing and forcing the tumour to lay still. This popularly came to be known as “Gated Radiotherapy”. With this technique, volume of normal tissue included decreased and dose of radiation could be increased. The radiation with this technique started giving good results so much so that it became a standard of care in early stage carcinoma lung when surgery was not possible. Yet, with this SBRT technique there was need for some margin normal tissue around the tumor during treatment, hence, the hunt was on for perfecting this technique which culminated in the development of CyberKnife(steroetactic Robotic Radiosurgery). Here, Gold seeds (being inert and with excellent density) are introduced into or around the tumour. These gold seeds, technically named as internal fiducials, acted as shadows for the movement of the tumour permitting the machine to know the exact location of the tumour, moment to moment, automatically. But the supreme aspect of CyberKnife technology was the development of automatic correction of the patient position if the tumour has moved from expected and placing the tumour in the expected path of beam. This technology was important because it potentially eliminated the need for giving the normal tissue margin around the tumour decreasing the possibility of side effects drastically and increasing the possibility of tumour control. The increase in the dose gave results better than expected and it was realized that the mechanism of action of radiation at higher dose per treatment was different and much more efficient in handling resistant cells. The machine that was developed mastering this technology was aptly named as CyberKnife. It is considered as knife, even though no scalpel was used, because it is capable of cutting of the tumor biologically from the word go. Subsequently, usually over 3 months tumor cells would either undergo rupture (apoptosis) or cell death, get digested and put out of body as waste products. At the end of 3 months, responding tumors will show metabolic activity near normal, with disappearance or significant reduction in size. Some damaged cells survive for long time try to multiply and after few multiplications give up and die.

With this background in mind and unwilling to undergo the surgery with the risks involved Mrs. Sharma flew in from Mumbai with PET CT scan and reports, for CyberKnife treatment. On Day two of the arrival, she underwent insertion of 4 gold seed fiducials, one inside the cancer and rest around it (with the knowledge of risk of possible pnumothorax – collection of air in the cavity around the lung which might have required a minor surgical procedure of insertion of tube inside the pleural cavity for a day or two in an occasional patient). She rested for 2 hours in the hospital and went back to hotel. She was given the option of flying back to Mumbai and return after 5 days. But she decided to enjoy the stay at Bangaluru. In day 7 treatment planning process started. A vacuum fixture, which takes the shape of the patient when air is sucked out of it, was prepared for her to keep her still as far as possible during the treatment. A planning PETCT scan was done and images were pushed to computer planning station. The cancer, normal tissues like lung, heart, spinal cord etc. were delineated and radiation dose to the cancer and maximum limits well with in the tolerance of the particular organ was prescribed. The plan was generated and checked in all aspects and approved plan was sent to the machine on Day 8. Mrs. Sharma was counseled about how to be in the treatment couch as comfortable as possible, and taken up for the first of the 3 sessions. Patient is positioned perfectly, moving fiducials are identified, respiratory movements are modeled, automatic patient corrections are set and robot started moving around from a safe distance under the watchful eye of the treating team. The procedure was repeated in subsequent 2 days and on Day 10 the treatment sessions was over. Next step was about after care. In radiation sensitive people and/or in those who have persistent infection of the throat and bronchus, this area might show up as pnumonitis (something similar to localized pneumonia), which might require a course of steroid and antibiotics. This can happen generally anywhere from 1 month to 6 months after the completion of treatment. The best way is to prevent this side effect. Therefore, Mrs. Sharma was counseled regarding the ways of preventing the infection, taking a course of antibiotics at the first sign of infection. She is also put on a drug for 3 months, which is expected to reduce this type of side effects. Brief discussion went on regarding the lifestyle changes to improve the body immunity.