In February this year we reported initial 4- and 5-year follow-up data from two US-based research teams on the use of stereotactic body radiation therapy (SBRT or CyberKnife radiation) as a treatment for prostate cancer. A new study from a Korean research group appears to confirm the earlier findings.
Kang et al. provide data from a retrospective analysis of SBRT in treatment of localized prostate cancer. Their patient cohort included 44 men — all treated at the Korea Cancer Center Hospital between October 2002 and December 2007. The patients were classified as low risk (n = 5), intermediate risk (n = 10 patients), or high risk (n = 29 patients). All patients were treated with between 32 and 36 Gy in four treatment fractions.
The results reported by Kang et al are as follows:
- Average (median) age of patients was 69 years (range, 53 to 79 years).
- Average (median) duration of follow-up was 40 months (range, 12 to 78 months).
- The 5-year prostate cancer-specific survival rate was 100 percent.
- The 5-year progression-free survival rate was 100 percent.
- At least follow-up the biochemical progression-free survival rates were
- 100 percent for the low-risk patients
- 100 percent for the intermediate-risk patients
- 90.8 percent for the high-risk patients
- Adverse effects of SBRT were
- 6 acute and 3 late grade 2 urinary toxicities
- 4 acute and 5 late grade 2 rectal toxicities
- There were no grade 3 or higher treatment-related toxicities.
Kang et al. conclude that SBRT is a safe and well tolerated forms of treatment of localized prostate cancer — even for relatively high-risk patients.
The key difference between the current study and the two previously-reported sets of data on US-based patients is that in the US cohorts all of the patients were classified as either low or intermediate risk, whereas two-thirds of the Korean patients discussed above were classified as high risk.
Clearly we shall need more data to get a sound understanding of the potential of SBRT as a treatment for patients with high-risk, localized prostate cancer. In addition, we still need longer follow-up on larger numbers of patients before we can be comfortable about the potential of SBRT in the treatment of localized prostate cancer, but good data do appear to be accumulating, and the initial potential of this type of therapy seems to be confirmed at the 5-year data point.
Filed under: Diagnosis, Management, Treatment Tagged: | body, localized, outcome, SBRT, stereotactic
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Please define specifically “localized prostate cancer” as against prostate cancer with invasion of the seminal vesicles.
Dear Mike:
The strictest definition of “localized” prostate cancer is most appropriately used to mean cancer that is confined to the prostate itself, i.e., organ-confined prostate cancer that is pathological stage T1 or T2. It is sometimes used to include prostate cancer that is confined pathologically to the prostate and the seminal vesicles. However, cancer that extends into the seminal vesicles — i.e., pathological T3 disease — would more properly be described as “locally advanced.”
Great results. We have many techniques to deliver high dose radiation to the prostate these days. Seems that the question would be more along the lines of what does the least collateral damage. If there is a difference in delivery methods vis a vis the cancer then it kind of flies in the face of radiation theory. That saying that radiation is pretty much just that (protons maybe somewhat different). Then some methods are missing cancer in the prostate. These are pretty high numbers, but if everyone is basically T1 even with a high PSA then I guess I could believe it. Many studies assign less value to stage than Gleason or PSA in predicting outcome, however. They did not mention hormones, critical info.