Patient Review Highlights
Dr. Debnarayan Dutta provides answers that are very helpful. THANK YOU
Radiation therapy is one of the most important tools to combat cancer. However, conventional radiation therapy is long course (usually 6 to 7 weeks) treatment and may have severe acute side effects including skin and mucosal reactions, diarrhea, feeding difficulties and others. Higher dose radiation is also not possible to deliver due to limitations related to toxicities. CyberKnife is a precise radiation therapy technique by which high dose radiation therapy can be delivered only to the tumor and minimal dose to the normal structures.
CyberKnife treatment is a short course treatment (usually only one to 5 days) and have no or minimal side effects. Many tumors which are ‘resistant’ to conventional radiation are ‘sensitive’ to high dose radiation delivered by CyberKnife. “CyberKnife has unique system that it can track moving tumors and treat them with immaculate accuracy”. Tumors in moving organs such as lung and liver can be treated most effectively CyberKnife. Dr Debnarayan Dutta, Consultant in Radiation Oncology at Apollo Speciality Hospital, Chennai commented “there are few tumors which were thought to be not treatable are now being treated successfully with CyberKnife”.
Master ShreeVaishnav, a 6 year old boy from Kerala suffering with choroidal haemangioma (eye lesion) had vision loss in both the eyes, he was referred from Sankar Netralaya for treatment. He was treated with CyberKnife and at 2 months follow up evaluation his vision had dramatically improved. “We are thankful to Dr Dutta for giving vision back to my son” told Shree Vaishnav’s father who was elated about CyberKnife. “CyberKnife has opened a modern and effective option for these diseases and we are happy with the result” said Dr Prativa Mishra, eye specialist involved in Shree Vaishnav’s treatment.
CyberKnife is a revolution in cancer treatment; it provides effective, short course, minimal toxic and high dose treatment in brain, lung, liver, pancreas, prostate, head and neck and many other tumors.
A fifty-four years old Marwari patient from Assam presented with progressive jaundice and intermittent episodes of abdominal pain for three months. CT scan of abdomen showed a small (1.5 x 1.5 cm) mass in the bifurcation of common bile duct which is causing biliary tract obstruction and hence jaundice. Portal nodes were not enlarged and there was no lesion in the liver parenchyma. At presentation, serum bilirubin level was high (14.7 mg/dl). Endoscopic biopsy and brushing cytology was adenocarcinoma and clinic-radiological diagnosis was ‘Klatskin tumour’.
- Metallic stenting was done to relieve jaundice and after stenting serum bilirubin level came down rapidly. PET scan showed increased uptake in the biliary duct region mass without any sign of metastasis. He was evaluated and planned for treatment with robotic radiosurgery. He was treated using robotic radiosurgery (CyberKnife) with high precision radiotherapy technique after fiducial placement (gold seeds) near the tumour. After one year, the patient had no obvious complain, liver function (no jaundice) was normal and CT scan evaluation showed completed resolution of the mass.
- Klatskin tumour is an uncommon tumour that arises from the bifurcation of common bile duct in the abdomen (duct that drains bile from liver). Patients usually present with progressive (increasing) persistent jaundice followed by pain in the upper abdomen. Surgical excision is the mainstay of treatment. However, surgery is not possible in majority of the patients owing to the location of the tumour, high jaundice and medical condition. Chemotherapy may not be an optimal option in majority of the patients as they present with high jaundice. Majority of such patients with poor medical condition are treated with only supportive care and prognosis is dismal (survival for a few months only).
- Patients with metallic stent have relief from jaundice but unfortunately in a few weeks time, the stent gets blocked with tumour growth. Patients again present with high jaundice and have severely impaired quality of life. They complain of severe itching of entire body, loss of appetite and succumb due to impaired liver function from high jaundice/obstruction. The treatment is to have a longer ‘jaundice-free period’ which in turn improves quality of life and possibly survival function as well.
- Stereotactic body radiation therapy’s high dose radiation ‘sterilizes’ the metallic stent and bile duct region. It is assumed that with radiation therapy, blockage of bile duct and stent is delayed and patients have longer jaundice-free period.In Klatskin tumour, CyberKnife allows to deliver high dose of radiation in a short duration to the target without significant morbidity. If you wish to discuss about any specific problem, you can consult an Oncologist.
Short course radiation therapy is the one of the most talked about subject in recent years and also a fascinating research zone. Hypofractionated radiation therapy is an old concept, but only in recent years with tremendous improvement in radiation therapy delivery technologies there is a significant visible surge in it’s applicability in clinical practice. Modern radiation therapy technology is capable of delivering high dose to the target while sparing majority of the adjacent critical structures. Hence, it is possible to deliver short course of treatment regimen with higher dose per fraction without increasing in toxicity. In brain tumours, radiosurgery with gamma-knife is considered standard of care in many of the clinical indications such as small meningiomas, acaustic schwannomas, residual low grade gliomas, AVMs and solitary/ oligo brain metastasis. Gamma-knife radiosurgery is in clinical practice for more than five decades.
There are several prospective and randomized studies (level I evidence) with long-term follow up data supporting the use of radiosurgery in these clinical indications. Other indications of radiosurgery are pituitary tumour, craniopharyngiomas, glomus tumours, chordomas and others. Robotic radiosurgery (CyberKnife®) is precision radiosurgery delivery system and an extension of gamma-knife system. CyberKnife uses the principle of gamma-knife, but with linear accelerator source instead of multiple cobalt sources. CyberKnife is capable to treating all tumours indicated for gamma-knife with similar accuracy.
This modern tool has some additional advantages from gamma-knife, such as
1) CyberKnife can use fractionated treatment, hence relatively larger tumours can be treated.
2) Require only thermoplastic mask, no need for invasive frame.
3) Has inverse planning system, can spare critical structure.
4) There is a ‘intra-fraction’ correction technology with imaging.
5) There is no need to change the source, hence may be more cost effective.
6) Can be used to treat extra-cranial tumours also. CyberKnife has a linear accelerator attached with a robot and is capable of treatment from various coplanar and non-coplanar field arrangements. CyberKnife has sub-millimeter accuracy and unmatched dose distribution.
The advanced technology behind CyberKnife uses image guidance technology and computer-controlled robotics to deliver and extremely precise dose of radiation to targets, avoiding the surrounding healthy tissue, and adjusting for patient and tumor movement during treatment. In conclusion, CyberKnife is an extension of gammaknife radiosurgery delivery system. This machine has immense promise to treat with short course regimens with high dose and improve local control without increasing toxicities. If you wish to discuss about any specific problem, you can consult an Oncologist.