Radiation for Lesions

In discussions with my physician regarding the lesions in my bones (in one case leading to rib fracture) we surveyed treatment possibilities. I was expecting to be referred for beam radiation since that was the treatment of choice for me on three prior occasions. Radiation is primarily for pain control rather than combating the cancer. I’ve had three instances of 14 day treatment plans in order to gain relief from pain at the top and bottom of my spine and in my pelvic region.

However, this time my physician suggested looking into an IV radiation method using either Samarium or Strontium. He favored Samarium and so the majority of this post concerns therapy with Quadramet, the brand name for Samarium.  Both are treated by the body similarly to calcium and are attracted to areas of enhanced cellular activity. In other words, there is a natural tendency for the body to direct the radioactive particles to damaged areas. The compound emits both medium energy beta particles and gamma photons which kill adjacent cells in much the same fashion as external beam radiation methodologies. The half life of the radioactive component is measured in hours and unabsorbed materials are excreted through urinary function. The treatment is suggested in cases where external beam activity stands a strong chance of affecting nearby tissue or material. Again, in my case, the lesion is so close to the lung that external beam technologies would likely burn portions of the lung. While this is not a great issue for those with healthy lungs, it is for people like me who have suffered significant loss of lung function (asthma, COPD, etc).

The treatment can have strong collateral effect on bone marrow which in turn reduces white cell production, in turn reducing immune system effectiveness. As with chemotherapies, patients are vulnerable to collateral infection and so blood testing of the patient in treatment is suggested on a daily basis. Unlike external beam radiation, Samarium treatment has shown no propensity to spawn new cancers, however it does produce certain side effects which, in varying percentages, can produce adverse events. These are reported by the FDA as:

Adverse events were evaluated in a total of 580 patients who received Quadramet® in clinical trials. Of the 580 patients, there were 472 men and 108 women with a mean age of 66 (range 20 to 87).

Of these patients, 472 (81%) had at least one adverse event. In a subgroup of 399 patients who received Quadramet® 1.0 mCi/kg, there were 23 deaths and 46 serious adverse events. The deaths occurred an average of 67 days (9 to 130) after Quadramet®. Serious events occurred an average of 46 days (1 – 118) after Quadramet®. Although most of the patient deaths and serious adverse events appear to be related to the underlying disease, the relationship of end stage disease, marrow invasion by cancer cells, previous myelotoxic treatment and Quadramet® toxicity can not be easily distinguished. In clinical studies, two patients with rapidly progressive prostate cancer developed thrombocytopenia and died 4 weeks after receiving Quadramet®. One of the patients showed evidence of disseminated intravascular coagulation (DIC); the other patient experienced a fatal cerebrovascular accident, with a suspicion of DIC. The relationship of the DIC to the bone marrow suppressive effect of Samarium is not known. Marrow toxicity occurred in 277 (48%) patients

Treatment is intravenous and is administered over a period of 60 seconds and is followed by a saline flush. Patients are encouraged to drink two cups of water at the time of injection and encouraged to push fluids and urinate as often as reasonable following treatment to reduce radiation exposure to the bladder. Treatment with Samarium and Strontium are very similar in their natures.

The treatment is interesting and frankly, I hadn’t heard of it before my hematologist suggested it. I thought I’d pass along what I’d learned about it since bone damage is so common to those of us who suffer from Multiple Myeloma.