A powerful radiation approach offered at Memorial Sloan Kettering is offering hope to people with inoperable tumors of the liver and pancreas that have not spread to other parts of the body. Pioneered by MSK radiation oncologist Christopher Crane, the technique is giving people with large tumors of the liver and pancreas hope for a cure or longer-term survival. At the very least, Dr. Crane says, it can buy them time until a clinical trial might be available.
Tumors in the liver and pancreas often cannot be removed through surgery because they are too close to major blood vessels. Conventional radiation doses and techniques are not able to control these tumors, but higher “ablative” doses are able to successfully control 90 percent of tumors, Dr. Crane explains. Delivering these higher doses to larger tumors is particularly challenging because it is more difficult to protect the liver, stomach, and intestine, which are nearby.
Most radiation oncologists instead choose palliative treatment and deliver only about half the cumulative radiation dose needed to kill every cancer cell and control the tumor.
“Patients who have no surgical option have historically been undertreated instead of receiving potentially curative doses of radiation,” Dr. Crane says. “Our extensive experience delivering ablative doses in the upper abdomen enables us to have the courage and confidence to give treatments that effectively control the tumor.”
One key to giving larger doses safely is spreading them over a greater number of treatment sessions. Radiation dosage is measured in units called grays (Gy). A standard treatment for a liver or pancreas tumor would typically be 25 to 33 Gy given in five sessions. At MSK, patients might receive 67.5 Gy in 15 sessions or 75 Gy in 25 sessions. Although each individual dose may be slightly smaller, the cumulative biological dose is high enough to control the tumor while sparing nearby normal structures.
Such large overall doses could carry too much risk for toxicity or complications. But MSK’s radiation oncologists have the expertise to deliver the treatment without harming normal tissue. In fact, the treatment rarely causes anything other than mild fatigue.
Another critical feature of the approach is the ability to control and account for the movement of nearby organs. The biggest challenge is addressing the movement of organs from one treatment to the next. For example, air in the bowel or stomach can affect the position of multiple organs.
When doctors look at the CT scan, they must be able to recognize changes in the patterns and interpret what they mean. This enables them to tell the difference between random, temporary motion and a more consistent shifting in position that requires a change in the treatment plan.
“The expertise needed for making these judgments can be developed only by working with a large number of patients,” Dr. Crane says. He is training a growing number of MSK radiation oncologists in the technique, including at MSK’s regional outpatient locations.