Concern about Long-Term Recurrences after SBRT

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Concern about Long-Term Recurrences after SBRT: More than We Might Expect?

http://blog.lungevity.org/2012/01/27/sbrt-recurrences/

January 27th, 2012 - by Dr. Jack West

A new report was just published by a Japanese lung cancer group (in Kyoto) that describes their new observation that a higher than expected proportion of their patients who underwent stereotactic body radiation therapy (SBRT) for an early (node-negative) lung cancer developed late recurrences, even well beyond five years (For those unfamiliar the focused radiation approach known as SBRT, is is a very good summary of the topic). Some Japanese centers have been among the real pioneers in SBRT, doing it for more than a decade, often on patients who had medical issues that made it difficult to have them undergo surgery. These early encouraging results have led to SBRT now being practiced around the world, based on favorable local control and outcomes going out at least a few years from the procedure. One current question is whether SBRT might ultimately be sufficiently effective to be a good alternative to surgery even for people who are very good surgery candidates.

The authors of this report, a group of radiation oncologists, noted that we may see late recurrences beyond the time when we’d be inclined to declare an early victory for SBRT. In general,if a patient is doing well for 3 to 5 years after diagnosis and the start of treatment, we become pretty optimistic that they are unlikely to have a recurrence later. They reviewed the long-term outcomes among 66 patients who underwent SBRT for node negative NSCLC from 1999 and 2005. The median follow-up was only three years, so in light of the fact that these treatments were done 6-12 years ago, this median presumable indicates that many people were lost to follow-up or died in the first few years.

As is commonly seen in retrospective reviews of patients who underwent radiation for early NSCLC, many of the patients who died (14 of 39) had other significant medical problems had no evidence of active cancer at the time of their death. Sixteen patients remained alive, with no evidence of disease looking beyond 5 years from the time of SBRT. But four of them (25%) had recurrences beyond that five-year milestone, and three of those four had recurrences more than eight years after treatment. In three of the four patients, the recurrence was in the same area as the treated cancer (while a single patient had both local and distant recurrence in another part of the body). As a benchmark, our experience with surgery for early stage NSCLC has demonstrated that the risk of recurrence beyond 5 years is about 5-7%.

It’s important to acknowledge that this represents a rather small group of patients and represents just the experience from just one center, even if it’s a center that has good experience with the SBRT strategy. The authors also caution that their radiation dose of 48 Gray (Gy) over 4 treatments is less than the 60 Gy over three fractions that is often used in some places today. Therefore, results could be different with these changes. Of course, no local treatment, whether the best surgery or radiation therapy, will be able to cure disease that is destined to recur distantly because of circulating micrometastatic disease that is outside of the range of these treatments. At this point, SBRT’s promise of potentially working as effectively as the historical gold standard of surgery for early stage non-small cell lung cancer still awaits a test of time to really clarify whether it looks very favorable beyond the first few years.