3-D VOLUMETRIC EVALUATION OF RESPONSE IN 117 METASTATIC BRAIN MELANOMAS TREATED WITH BEAM-SHAPE RADIOSURGERY
C. BOSKOS(1,2), A. GORGULHO(1), Ch. VALERY(3), M.A. DE PAIVA(1), M.T. SELCH(1), N. AGAZARYAN(1), G. BOISSERIE (3), Α. DE SALLES(1).
(1) UCLA, Radiosurgery Department, Los Angeles, California, USA
(2) 251 General Hospital of Airforce, Oncology Department, Athens, GREECE.
(3) Hôpital Pitié-Salpêtrière, Radiosurgery Department, Paris, FRANCE
Introduction: We report retrospectively the response of melanoma brain metastases treated with stereotactic radiosurgery (SRS) in UCLA Radiosurgery Department, evaluating the volumetric changes from the day of treatment.
Patients
and methods: We evaluate 117 melanoma brain metastases in 39 patients
(28 male, 11 female) treated with SRS. We use for SRS treatment a
Novalis® 6 MV, with micro multileaf collimator M3® and software iPlan3®.
The volumetric study of these patients was based on MRI images before
and after SRS. Patients are selected with minimum follow up of 5 months
and at least 2 MRI in this interval. Median follow up was 9.16 months
(5.1 – 41.7). We induce the term of “speed of shrinkage” and “speed of
growth” as the ratio between percentage of shrinkage or growth
respectively and the interval. “Volumetric response” defined as decrease
of the volume (shrinkage).
Median prescribed peripheral dose was
18Gy (range: 10-25) to the 90% prescription isodose line. Median age was
52 years (range: 27-77), median grade of Karnofsky index was 90 (range:
60-100) and mean volume 2.25 cm³ (range:0.03-32.23). Overestimated
increased contrast enhanced volume was found in 6 hemorrhagic metastases
which was excluded from the study
Results: Volumetric response
reported in 95.3% of metastases with a mean delay to response 3.13
months (median 3.25). A subgroup of initially responding metastases
(13.9%) finally relapsed with a mean delay of 7 months (median 6.69).
According to Kaplan-Meier analyses, actuarial LC for 6-month, 1-year and 2-years was 91.6%, 82%, 77.6% respectively.
For
“LC group” median percentage of shrinkage was 80% (mean: 71%) and
median speed of shrinkage 8%/month (mean: 9%). For “Relapsed group”
median percentage of growth was 205% (mean: 191%) and median speed of
growth 28.7%/month (mean: 98).
Small initial volume and increased speed of shrinkage found to be favorable predictor factors for complete response.
Conclusions: According to the accurate volumetric evaluation of melanoma brain metastases, SRS found to be an efficient therapeutic approach, in terms of decreasing volume, with a median delay for response 3.13 months. Speed of shrinkage and initial tumor volume are favorable predicting factors for complete response.