SABR/SABRT for inoperable early-stage lung cancer

Surgery is the recommended option for early-stage lung cancer. However, a significant number of patients present with advanced age, comorbid medical illness, poor baseline pulmonary function, rendering them ineligible for surgical treatment.

In the absence of a curative surgical option, non-surgical radiotherapy has demonstrated notable survival benefit. The current National Comprehensive Cancer Network (NCCN) guidelines recommend Stereotactic Arc Body Radiation/Stereotactic Body Radio Therapy (SABR/SBRT) as an appropriate option for patients who are medically inoperable or at high surgical risk.

For patients having moderate-to-severe heart or lung comorbidities, SABR/SBRT often is the sole locoregional treatment option.  

Stereotactic ablative radiotherapy (SABR), also known as stereotactic body radiation therapy (SBRT), is a highly focused radiation treatment that gives an intense dose of radiation concentrated on a tumor, while limiting the dose to the surrounding organs. It is now the standard treatment with a curative-intent option for early-stage non-small cell lung cancer.

It offers high rates of in-field tumor control without the possible complications of invasive surgery. Multiple  studies have indicated an effectiveness and accuracy of up to 90% local tumor control. A standard dose varies from 48 to 60 Gy (unit used to measure the total amount of radiation that the patient is exposed to) given in five or less treatment sessions given within 2 weeks.

Overall survival has been shown to be better after SABR/SBRT than after other conventional radiation therapies suggesting high rates of long-term disease control. Another main benefit of SABR/SBRT in inoperable early-stage lung cancer is its safety profile characterized with low rates of treatment-related adverse events.   

The initial step in selecting patients for SABR/SABT involves taking multiple imaging scans as the first requirement for patient selection for SABR/SBRT.

CT, MRI and PET scans not only provide the precise location of the tumor, but also the health of the nearby structures crucial for minimizing the risk for possible radiation side effects. SABR/SBRT uses cutting edge image guidance technologies to ablate tumours, with sub-millimetre-scale accuracy while intensifying the radiation dose. This is the primary advantage of SABR/SBRT over other modalities, particularly when critical structures are located near the treatment area.

SABR/SBRT is non-invasive, painless and well-tolerated procedure ensuring patient comfort during the entire procedure. During the procedure the staff will instruct the patient not to move too much or special breathing techniques so that the radiation is given more accurately to the tumor target area.

SABR/SBRT is an outpatient service requiring about half to an hour visit to the hospital without hospital stays. Treatment courses are generally completed in 1-5 days, allowing patients to plan even if they are travelling from a distance. This results  in little or no interruption of their scheduled chemotherapy or other cancer treatments.

Side-effects to the treatment are  short-term and include feeling tired for a few weeks after treatment or nausea on the days of treatment. This is mitigated by asking the patient to take good nutrition, adequate rest and anti-emetics. However, it is important to emphasize that the benefits of SABR/SBRT for inoperable early-stage lung cancer far outweigh the potential risk for such side-effects.