RADIOTHERAPY WITH CYBERKNIFE
Advances in Radiation Therapy:
The treatment of cancer with radiation has moved leaps and
bounds since the discovery of X rays in 1895 by Wilhelm
Roentgen.Radiation therapy or radiotherapy is treatment by high
energy photons or X rays. This treatment is highly localised,
painless , non-invasive & bloodless.The treatment is done with the
help of highly sophisticated machines called Linear accelerators (
Linacs).In the last 20 years many innovations have happened that
have made the treatments safer, faster, & more precise.A recent
addition to our armamentarium is the all new advanced Cyberknife
S7 Stereotactic Radiosurgery System at Ruby Hall Clinic, Pune.
The entire emphasis for radiation therapy today is to make
treatments safer with reduction of adverse events & reducing time
of treatments from weeks to days so that the patients are more
comfortable during the entire process. There are many sites where
treatments have shorter protocols now like breast (from 6 to 4
weeks) & Prostate (from 8 to 4 weeks), and adoption of SBRT in
many sites has shortened this even further to 5 days like for
cancers of Prostate, Pancreas & Lung.
As per the National Cancer Registry of India, the incidence of new
cancer cases was between 90-100 per 1 lac individuals for 2020, an
estimate which is projected to increase and 1 in 9 Indians may be
affected by this disease by 2025. Radiation oncology forms an
integral part of cancer care and treatment goals can be cure or
relief of symptoms based upon the stage of the cancer. IN the last
2 decades there have been immense advancements in the delivery
of radiotherapy. The treatment planning and delivery has become
more conformal to the tumor with the reduction of side effect
profile. Treatment delivery is a completely painless, non invasive
and bloodless procedure & is delivered daily on OPD basis. After
the treatment for the day is done the patient can go home.There is
usually no immediate observation required after the treatment.
As we are moving to an era of highly personalized & targeted
treatments the indications for Stereotactic treatments is also
increasing.The goal of treatment is delivery of high doses of
radiation to tumor with curative intent while finishing it quickly like
a surgical procedure. The lack of a surgical incision, avoidance of
hospital stay and excellent disease free and control rates are now
making stereotaxy a mainstream treatment especially in recurrent
and limited metastatic disease settings.
CYBERKNIFE S7: Gold standard for Stereotactic radiotherapy treatments
The CyberKnife S7 System provides clinicians with critical
capabilities to deliver personalized stereotactic radiosurgery (SRS),
stereotactic body radiotherapy (SBRT), and hypofractionated
radiotherapy treatments anywhere in the body. The Cyberknife S7
is the only radiation delivery system that features a linear
accelerator (linac) directly mounted on a robot to deliver the
high-energy x-rays or photons used in radiation therapy. It also
has hundreds of degrees of freedom such that the robot moves and
bends around the patient, to deliver radiation doses from
potentially thousands of unique beam angles.
This state of the art machine is a fully automated, AI-driven,
treatment delivery system with real time motion adaptation and
dynamic dose delivery. The most impressive feature is the real time
tumor tracking in which the robot can track the tumor while
delivering the treatment and it auto adjusts for the movement
especially in tumors that are continually moving with respiration
like lung & liver tumors.This keeps the patient breathing normally
during the treatment & completely at ease. All this & the treatment
is delivered with Submm Accuracy which is required for the high
doses that are delivered in SRS treatments.
Cyberknife Treatment- Indications
The many indications for SRS/SBRT treatments include:
1. Brain tumors like Meningioma, Acoustic Schwanomma,
Glomus Jugulare, Brain metastases, Arteriovenous
Malformations, Trigeminal Neuralgia, etc.
2. Lung tumors- Early localized Lung cancers, Lung metastases.
3. Spine tumors like metastases, Benign tumors, Spinal AVMs.
4. Liver & Pancreatic Tumors.
5. Prostate Cancers can also be effectively treated with SBRT
protocols.
CYBERKNIFE IN GASTROINTESTINAL MALIGNANCIES
1. Liver Tumors: Liver metastases; Unresectable Heapatocellular Cancers; Portal Vein Thrombosis
2. Pancreatic Cancers: Localised primary or recurrent pancreatic cancers.
3. Lymph nodal recurrences: Any isolated lymph nodal recurrence from gastrointestinal or genitourinary cancers can be focussed for SBRT
4. Recurrent rectal cancers in pelvis region which can be targeted for SBRT.
5. Prostate cancers (localised) can also be targeted with cyberknife for SBRT.
The tumors that can be targeted by SBRT have to be carefully selected and treatment plans are individualised. For examplefor liver tumors mandatory requirement is Pathological confirmation of HCC; at least one radiological image showing the classic HCC enhancement with alpha fetoprotein (AFP) >200 ng/ml or at least 2 radiological findings (CT/MRI/Angiogram) showing the classic HCC; the presentation of unresectable or medically inoperable HCC, and ECOG performance status of ≤ 2.
Before treatment gold fiducial markers need to be implanted percutaneously around the perimeter of the target volume 5-7 days before the planning CT-scan. Cyberknife robotic radiotherapy with synchrony respiratory tracking capabilities allows more accurate targeting by reducing the margin of error and normal tissue exposure during therapy and therefore increases the chances of treating larger tumors with limited normal liver volume available or tumors in close proximity to critical organs. High doses need to be given to the tumors where tumor size can range from 1-15 cm but there is an important requirement that the healthy liver should be sufficient & doses to a minimum volume of 700 ml should receive a total dose less than 15 Gy.
Similarly, pancreatic cancers which are considered locally limited but inoperable are being increasingly treated with SBRT instead of the conventional 25-28 days treatments. This is usually given in combination with high dose chemotherapy before or after the SBRT treatments. Such an approach allows for radiation to be finished quickly while allowing for full dose of chemotherapy & shows better local control.
SRS/SBRT Treatments- Is it actually needed? Stereotactic radiosurgery SRS or SBRT treatments are used to treat cancers & functional abnormalities across body with highly focussed high doses of radiation per sitting with the goal of controlling cancer growth while minimizing radiation to surrounding normal tissue; to Preserve & improve neurological functions & to Preserve Quality of life. As cancer treatments are getting advanced & more effective the lifespan is increasing. Now even a stage 4 lung cancer can live a healthy life with only a daily tablet. Due to this increase in lifespan patients can have multiple recurrences which require retreatments that can need repeat radiotherapy sessions. In such cases that require reirradiation cyberknife is a very useful tool with its submm accuracy & live motion tracking features. With recent advances in treatment, cancers which are diagnosed upfront with 1- 5 metastatic sites which can be targeted & treated along with primary treatment are considered as oligometastatic & are considered curative. Such cancers are increasingly being targeted with SBRT for radical treatment and can be cured also.
RUBY HALL CLINIC- Radiotherapy department. The radiation oncology department at Ruby Hall Clinic, Pune houses 3 world class machines for the cancer treatment which includes a Trubeam STx 2.0, Halcyon Elite and CyberKnife. We routinely treat all sites of cancers and boast of a strong stereotaxy program which has been strengthened by the arrival of AI platform with the installation of CyberKnife. The costs involved in the treatment is highly variable and is dependent upon the technique availed. A discussion is always required to understand what radiotherapy treatment is indicated and the goals of treatment