ESTRO 2022

Session Item

Sunday

May 08

10:30 - 11:30

Poster Station 2

12: GI

Chair: , Italy

Session Type: Poster Discussion

Track: Clinical

Journey:

Outcomes and hemato-immunological toxicity in anal cancer patients with or without HIV infection

Christian Velten, USA

Presentation Number: PD-0500

Abstract

Abstract Title:

Outcomes and hemato-immunological toxicity in anal cancer patients with or without HIV infection

Authors:

Christian Velten¹, Patrik Brodin¹, Megi Gjini¹, Shaoyu Zhu², Matthew Hauze³, Shalom Kalnicki³, Chandan Guha¹, Madhur Garg³, Rafi Kabarriti¹

¹Albert Einstein College of Medicine and Montefiore Medical Center, Radiation Oncology, Bronx, USA; ²Albert Einstein College of Medicine, Radiation Oncology, Bronx, USA; ³Montefiore Medical Center, Radiation Oncology, Bronx, USA

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Purpose or Objective

Compare the outcomes, occurrence of hemato-immunological toxicity, and their association with dose to active bone marrow (ABM) after definitive chemoradiation for patients with anal cancer living with HIV (PLWH) or without HIV infection (HIV-).

Material and Methods

Patients treated for anal cancer at a single institution between 2007-2020 were identified and hemato-immunological and clinical data were tabulated. Dose to ABM was evaluated by overlaying bone contours within the irradiated volume on pre-treatment PET/CT scans. Areas of bone with SUV exceeding the mean bone SUV were designated as ABM. Evaluated hematologic quantities were pre-treatment values, value at and time to nadir (TTN) and recovery (TTR), and occurrence of grade ≥3 hematologic toxicity.

Results

97 patients with anal cancer were identified, of which 44 were PLWH. Complete CBC counts were available for 90 patients. Radiation therapy was commonly prescribed to 50.4-54 Gy using IMRT; 3 patients underwent RT alone (all PLWH); Chemotherapy was 5-FU+Mitomycin-c (34 HIV-/27 PLWH), Capecitabine+Mitomycin-c (16 HIV-/11 PLWH), or other (3 HIV-/3 PLWH).

Median follow-up was 55 months in HIV- patients (rg: 10-150) vs. 59 months in PLWH (rg: 5-164). Among HIV- patients there were 45% stage I/II and 55% stage III, in PLWH there were 40% stage I/II and 60% stage III. There were 10/53 vs. 7/44 loco-regional recurrences in the HIV- vs. PLWH group, 9 vs. 2 distant metastases, and 9 deaths in both. Outcomes (HIV- vs. PLWH) were comparable with 2‑year PFS at 76.9% vs. 83.8% (p=.40) and OS at 92.3% vs. 92.8% (p=0.93). Substitution of 5-FU with capecitabine had no effect on outcomes in either group (p>0.73).

G3+ Lymphopenia occurred in 83% (n=44) vs. 89% (n=32) (p=.35), G3+ neutropenia occurred in 21% (n=11) vs. 56% (n=20) (p<.01), and G3+ thrombocytopenia occurred in 8% (n=4) vs. 33% (n=12) (p<.01) of patients in the HIV- and PLWH groups, respectively. Absolute ABM V_5Gy to V_40Gy was associated with delayed recovery in platelet counts for HIV- (0.40‑0.56; p≤.04) and PLWH (0.41; p=.04) patients (Fig.1), with a sharp increase at volumes above 275cm³ (HIV-) and 350cm³ (PLWH), while rel. V_5Gy (-0.29; p<.04) for HIV- and abs. V_5Gy to V_40Gy (-0.43; p≤.02) for PLWH were associated with a more rapid drop in lymphocytes showing no threshold (Fig.2).

Figure 1. Time to recovery association with ABM V_5Gy and V_15Gy.

Figure 2. Time to nadir association with volumetric ABM dose metrics.

Conclusion

Survival outcomes after definitive chemoradiation were comparable between HIV negative and HIV positive patients, but PLWH had higher rates of G3+ neutropenia and thrombocytopenia. Dynamics of hematologic toxicity showed significant association with the irradiated volume of ABM with stronger and continuous correlation of TTN in lymphocyte count in PLWH. Platelet dynamics suggest volume thresholds affecting TTR in both groups. Strategies to improve functional bone marrow sparing including dose de-escalation in low-risk disease are ongoing.