One of the lung cancer surgeons I work closely with sent me and a couple of the radiation oncologists at my center a report that just came out from a group in Kyoto highlighting that they have a seen a notable proportion of their patients develop late recurrences, even well beyond five years, among their patients who underwent stereotactic body radiation therapy (SBRT) for node-negative early stage NSCLC many years earlier (see Dr. Loiselle's great summary of SBRT for a review of the topic). Many Japanese centers have been pioneers in SBRT, doing it for more than a decade, but over the past 3-5 years the strategy has become far more widely practiced, based on very encouraging local control and outcomes going out several years, which lead to the question of whether SBRT might be an effective and alternative to surgery (hence the keen interest among thoracic surgeons about whether newer radiation techniques will lead to reduced demand for their services). The authors of this report, who are radiation oncologists, highlight that it's possible we'll see late recurrences beyond the time when we'd be inclined to declare a victory for SBRT. In general, if we see patients doing well 3-5 years after diagnosis and the start of treatment, we begin to think we're getting out of the woods.
The longer-term outcomes for a total of 66 patients who had undergone SBRT for node negative NSCLC between 1999 and 2005 were reviewed, though the median follow-up was only three years. Given the fact that these treatments were done 6-12 years ago, this median reflects that many people were lost to follow-up or died in the first few years. As is typical for retrospective reviews of patients who underwent radiation for potentially resectable 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 and without evidence of disease beyond five years from the time of SBRT, and the authors noted that four of them (25%) had recurrences beyond that point -- in fact, three of the four had recurrences more than eight years after treatment. In three of the four cases, the recurrences were local (one patient had both local and distant recurrence in another part of the body). Past history with surgery for early stage NSCLC has generally shown that the risk of recurrence beyond 5 years is in the range of 5-7%.
This isn't a large series of patients, and it's the experience from just a single (well experienced) center. They also note that the dose used (48 Gray (Gy) over 4 treatments is less than the 60 Gy over three fractions that is often used in some places now, so results could be different with these different techniques. Of course, no local treatment -- neither excellent surgery nor the best radiation therapy -- will cure disease that is destined to recur distantly from micrometastatic disease outside of the local area visible on scans. But the promise of SBRT, of providing comparable long-term local disease control and perhaps working as effectively as the historical gold standard of surgery, still awaits a test of time to really clarify whether it looks very favorable beyond the first few years.