The Microvascular Health Status Predicts Radio-Induced Acute Toxicities in Breast, Prostate and Head and Neck Cancer Patients

PURPOSE/OBJECTIVE(S)

investigate the role of healthy/unhealthy microcirculation in predicting acute toxicity (tox) after breast (BC), prostate (PC) and Head & Neck (HNC) cancer RT.

MATERIALS/METHODS

We enrolled BC patients (pts) treated with hypofractionated-RT after conservative surgery (42.4 Gy + 10 Gy boost to tumor bed), PC pts receiving radical-RT (65 Gy / 25 fractions), HNC pts treated with conventional RT (54-70 Gy @ 1.8-2 Gy/fr) or moderately hypofractionation (56.1-69.96 Gy @ 1.7-2.12 Gy/fr). We assessed baseline sublingual-microvasculature (MV) health status before RT using a sidestream dark-field camera coupled to the GlycoCheck™ software. The system records videos showing the live movement of red blood cells (RBCs) in the microvessels. It computes 5 functional parameters: (a) perfused boundary region (PBR) estimating the penetration of RBCs into the permeable part of the endothelial glycocalyx (higher PBR values result from damaged glycocalyx, indicating impaired microcirculation); (b) density of capillaries (1/mm2); (c) blood flow in the recorded area (103 μm3/s/mm2); (d) recruitment capacity (quantifying the ability to recruit additional capillaries); (e) a global MV_HealthScore (MVHS), higher values indicate healthier MV. MVHS is computed by weighting information from the previous parameters. The computation of MVHS needs a prolonged video acquisition not reached by less compliant patients. Endpoint for this analysis was acute tox. We selected a clinically relevant tox endpoint for each cancer site: grade≥2 erythema (G2+E) for BC, any grade≥3 tox (G3Tox) for HNC and persistent grade≥1 tox simultaneously present in gastrointestinal and genitourinary domains (G1+GIGU) for PC. We used logistic regression to assess MV functional parameters' association with toxicity.

RESULTS

We evaluated 63 BC, 38 PC, 39 HNC pts. 77 (55%) had an evaluation for MVHS. 23/63 BC pts presented with G2+E, 12/38 PC pts with G1+GIGU, 12/39 HNC pts with G3Tox. Average MVHS was 3.6, 3.2, 2.7 in BC, HNC and PC, respectively (P>0.15). The MVHS associated with tox: healthy MV protects from tox (continuous, OR = 0.66 for 1 point increase, p = 0.01, AUC 0.69). Categorizing pts as low MVHS (<2.5), average MVHS (2.5-6.5) and high MVHA (>6.5), the observed toxicity rates in the 3 classes were 50%, 26%, 0% (p = 0.02). Also, a 3-variate model including the separated functional parameters predicted tox (AUC 0.67) on the 144 pts: higher PBR is a risk (OR = 7.6), higher capillary density protects (Logarithm, OR 0.002), higher blood flow is a risk (Logarithm, OR = 14.2).

CONCLUSION

These data suggest an interaction of compromised MV with repair mechanisms. The MVHS model predicts acute toxicity in BC/PC/HN pts proving (i) a quantitative relationship between MV state and radio-susceptibility and (ii) in an organ-agnostic way. The systemic functional information derived by the sublingual microscope could boost the personalization of predictive models and tailor them to the single-patient functional status. Funded by AIRC IG 21479.

Moderate Hypofractionation with Simultaneous Integrated Boost in Prostate Cancer: Long-term Results of a Phase I-II Study

AIMS

To report 5 year outcome and late toxicity in prostate cancer patients treated with image-guided tomotherapy with a moderate hypofractionated simultaneous integrated boost approach.

MATERIALS AND METHODS

In total, 211 prostate cancer patients, 78 low risk, 53 intermediate risk and 80 high risk were treated between 2005 and 2011. Intermediate- and high-risk patients received 51.8 Gy to pelvic lymph nodes and concomitant simultaneous integrated boost to prostate up to 74.2 Gy/28 fractions, whereas low-risk patients were treated to the prostate only with 71.4 Gy/28 fractions. Daily megavoltage computed tomography (MVCT) image guidance was applied. Androgen deprivation was prescribed for a median duration of 6 months for low-risk patients (for downsizing), 12 months for intermediate-risk and 36 months for high-risk patients. The 5 year biochemical relapse-free survival (bRFS), cancer-specific survival (CSS), overall survival and late gastrointestinal and genitourinary CTCAE.v3 toxicity were assessed. The effect of several clinical variables on both outcome and gastrointestinal/genitourinary toxicity was tested by uni- and multivariate Cox regression analyses.

RESULTS

After a median follow-up of 5 years, the late toxicity actuarial incidence was: genitourinary ≥ grade 2: 20.2%; genitourinary ≥ grade 3: 5.9%; gastrointestinal ≥ grade 2: 17%; gastrointestinal ≥ grade 3: 6.3% with lower prevalence at the last follow-up visit (≥ grade 3: genitourinary: 1.9%; gastrointestinal: 1.9%). Major predictors of ≥ grade 3 genitourinary and gastrointestinal late toxicity were genitourinary acute toxicity ≥ grade 2 (hazard ratio: 4.9) and previous surgery (hazard ratio: 3.4). The overall 5 year bRFS was 93.7% (low risk: 94.6%; intermediate risk: 96.2%; high risk: 91.1%), overall survival and CSS were 88.6% (low risk: 90.5%; intermediate risk: 87.4%; high risk: 87%) and 97.5% (low risk: 98.7%; intermediate risk: 95%; high risk: 94.3%), respectively. Risk classes and androgen deprivation were not significantly correlated with either bRFS, overall survival or CSS. Twelve patients experienced a biochemical relapse but none experienced clinically proven local and/or pelvic recurrence.

CONCLUSION

A satisfactory 5 year outcome with an acceptable toxicity profile was observed. The combination of image-guided radiotherapy-intensity-modulated radiotherapy, high equivalent 2 Gy dose (EQD2) with a moderate hypofractionated approach and extensive prophylactic lymph node irradiation also leads to very good outcome in high-risk patients.