Hematologic toxicity in patients treated with post-prostatectomy whole-pelvis irradiation with different IMRT techniques is not negligible and prolonged: preliminary results of a longitudinal, observational study

Publication date: Available online 28 January 2016
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Cesare Cozzarini, Barbara Noris Chiorda, Carla Sini, Claudio Fiorino, Alberto Briganti, Francesco Montorsi, Nadia Di Muzio
ObjectiveTo address the thus far poorly investigated severity and duration of hematologic toxicity (HT) from whole-pelvis radiotherapy (WPRT) in a cohort of chemo-naïve patients treated with post-prostatectomy radiotherapy including WPRT with different IMRT techniques, doses and fractionations.Methods and MaterialsThis analysis pertains to 125 patients (70 from a pilot study and 55 from an observational protocol) for whom one baseline and at least 3 subsequent blood samples (median 6), obtained at irradiation mid-point and end, and thereafter at 3, 6, and 12 months, were available. Patients were treated with adjuvant (n=73) or salvage intent, static-field IMRT (n=19), VMAT (n=60) or helical Tomotherapy (n=46), conventional (n=39) or moderately hypofractionated (median 2.35 Gy/fr, n=86) regimens. The median EQD2 dose to the prostatic bed was 70.4 Gy, to the lymph-nodal PTV (PTVLN) 50.2 Gy. Clinical and dosimetric data were collected.ResultsBoth leukopenia and thrombocytopenia were significant (median nadir count 65% and 67% of baseline, respectively), leukopenia also persisting (1-year median count 75% of baseline). Lymphopenia was the major contributor to severity and 1-year persistence of leukopenia: all patients developed acute Grade ≥1 lymphopenia (61% and 26% Grade 2 and ≥3, respectively), while 1-year Grade ≥2 lymphopenia was still present in 16%. Multivariable analyses highlighted, in addition to an independent predictive role of corresponding baseline values, that of higher EQD2 doses to PTVLN for the risk of acute neutropenia, of hypofractionation for acute thrombocytopenia, of older age for acute Grade 2 lymphopenia and, interestingly, of smoking for 1-year Grade ≥2 lymphopenia, with no role for different IMRT techniques.ConclusionsLeukopenia and lymphopenia after post-prostatectomy WPRT were found to be less negligible and more prolonged than expected. A number of radiation-related and clinical factors favoring HT, whose awareness may be crucial when prescribing WPRT, in particular if concomitant to chemotherapy, were individuated.

Teaser

Leukopenia and, especially, lymphopenia, after post-prostatectomy radiotherapy including whole-pelvis irradiation (WPRT) were found to be far more severe and prolonged than expected. In addition to baseline values, older age and smoking were independently predictive of acute and 1-year Grade 2 lymphopenia, respectively. This finding should be carefully taken into account when advising a still highly debated treatment such as WPRT, given increasing evidence of possible correlation between treatment-induced lymphopenia and increased risk of tumor progression.


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