Is kidney cancer really so resistant to radiation? Many studies indicate that kidney cancer is far more resistant to radiation therapy than many other cancers. RCC just doesn’t behave as other cancers do, so the most knowledgeable doctors use radiation very carefully. The typical wider damage that comes with general radiation is not balanced by a good response in RCC. To be effective, a more specialized radiation is needed.
One of my most knowledge SmartPatients/friend has provided important information about radiation and RCC. The following is a link to videos, and is followed by advice to a fellow patient trying to understand her options. SBRT is Stereotactic Body Radiation Therapy, and not at all the same as general radiation, as is explained..
“For right now let me sort of define whats important about SBRT and why it works on RCC. SBRT is all about high daily dose needed for radioresistant cancers.
What is important is the high daily dose for RCC used in SBRT. For example, an SBRT plan for a lung met will use 3 fractions x 15 Gy/day or 5 fractions x 10 Gy/day. Fields will be very conformal to the tumor (but usually not by using shaped fields)
Forget shaped. Conformal small fields–yes.
An IMRT (Intensity-modulated radiation therapy) or shaped conventional plan might use 25 fractions x 10 Gy/day.
And to give daily doses of 15 Gy you need excellent imaging and mechanical capability that not every machine has.
Does it matter? Yes! The recurrence rate for RCC is much higher with low daily doses. The SBRT dose regimes will give about 90% local control (meaning that met never comes back-if you get cancer, it is a new spot.) Standard dose regimes give more like 60% long term local control.
SBRT typically uses dose modulation(which may or may not involve shaping beams ) to control where dose goes.
MLC or block shaped beam IMRT IMRT/IGRT-all use shaped beams but are not SBRT.
Cyberknife and Gammaknife, for example, use no beam shaping-they use hundreds of tiny identical circular pencil beams to build dose covering the tumor.
ANALOGY: Let’s say you have a huge thistle in your lawn. And you have a cup of Roundup. You can go outside 3 days in a row and put 1/3 of a cup on it. Or you can go out every other day for a month and put a spoonful on it. You are more likely to kill it for good with the first method. We want a quick thorough cell kill.”
This SmartPatient does not mince words. We all want a quick through cell kill, which may bring a met under control permanently. Not mentioned in this article, is that the body can also have an immune response in the area of the radiation, and deliver a burst of its own cancer-fighting proteins to the area. This can have an additional effect in countering those super-tiny mets that may be invisible, or just trying to establish themselves in the neighborhood.
Just as there are a range of antibiotics, and we know that the choice of each is dependent up the infection, its location, and the individual’s system, so it is with radiation therapy. Properly chosen, delivered correctly and to the exact place, with an understanding of the person’s disease, it may be a very effective tool to fight RCC, and not just clear cell.