Definitive local therapy for T4 prostate cancer associated with improved local control and survival.

OBJECTIVES: To evaluate patients with clinical (c)T4 prostate cancer (PCa), which represent both a heterogenous and understudied population, who often present with locally advanced disease and obstructive symptoms causing significant morbidity and mortality. We analysed whether receiving definitive local therapy influenced symptomatic and oncological outcomes. METHODS: Retrospective analysis of 154 patients with cT4 PCa treated at a single institution in 1996-2020. Systemic therapy with or without local treatment (surgery, radiotherapy [RT], or both). Uni- and multivariate analyses of associations between clinicopathological features (including obstructive symptoms) and receipt of local therapy on overall survival (OS) and disease control were done with Cox regression. RESULTS: The median follow-up time was 5.9 years. Most patients had adenocarcinoma (88%), Gleason score 9-10 (77%), and median baseline prostate-specific antigen (PSA) of 20 ng/mL; most (54%) had metastatic cT4N0-1M1 disease; 24% regionally advanced cT4N1M0, and 22% localised cT4N0M0. Local therapies were RT (n = 44), surgery (n = 28), or both (n = nine). Local therapy was associated with improved OS (hazard ratio [HR] 0.3, P < 0.001), longer freedom from local recurrence (HR 0.39, P = 0.002), less local progression (HR 0.41, P = 0.02), fewer obstructive symptoms with progression (HR 0.31, P = 0.01), and less death from local disease (HR 0.25, P = 0.002). On multivariate, local therapy was associated with improved survival (HR 0.58, P = 0.02), and metastatic disease (HR 2.93, P < 0.001) or high-risk pathology (HR 2.05, P = 0.03) was associated with worse survival. CONCLUSION: Definitive local therapy for cT4 PCa was associated with improved symptomatic outcomes and survival even among men with metastatic disease. Pending prospective evaluation, these findings support definitive treatment with local therapy for cT4 disease in select cases.

Increased Frequency of Mesorectal and Perirectal LN Involvement in T4 Prostate Cancers.

PURPOSE: Patients with prostate cancer presenting with advanced T stage, mainly T4, might have a unique pattern of nodal failure and disease involvement that is not typically covered when local therapy is offered. We attempted to identify common sites of nodal disease presentation and failure for patients presenting with cT4 prostate cancer. METHODS AND MATERIALS: All patients with treatment-naïve cT4 prostate cancer were retrospectively identified. All patients were required to have a confirmed diagnosis reviewed by our genitourinary pathologist and completed baseline staging. Lymph node (LN) involvement and location at diagnosis were reviewed by a genitourinary radiologist. All patients' follow-up scans were also reviewed; based on LN size, imaging characteristics, and progression/regression characteristics on systemic therapy, the locations of sites of LN failure were recorded. For patients who underwent surgery, any pathologically involved LNs and their anatomic locations were recorded. A total of 103 patients met these criteria, with a median follow-up of 8 years (range, 0.5-14 years). RESULTS: Rectal involvement by the primary disease was associated with a higher risk of perirectal and mesorectal LN involvement (45%) relative to no rectal involvement (26%) (P < .05). These echelons are typically not covered with conventional pelvic external beam radiation therapy and are not routinely part of pelvic LN dissection in patients treated surgically. Conversely, bladder or pelvic side wall invasion did not correlate with increased frequency of involvement of perirectal/mesorectal LNs (P > .05). CONCLUSIONS: When offering local therapy, target modification to include the perirectal and mesorectal LNs should be considered for patients presenting with T4 prostate cancer with rectal involvement.

Protein kinase C inhibitors sensitize GNAQ mutant uveal melanoma cells to ionizing radiation.

PURPOSE: Uveal melanoma (UM) tumors require large doses of radiation therapy (RT) to achieve tumor ablation, which frequently results in damage to adjacent normal tissues, leading to vision-threatening complications. Approximately 50% of UM patients present with activating somatic mutations in the gene encoding for G protein αq-subunit (GNAQ), which lead to constitutive activation of downstream pathways, including protein kinase C (PKC). In this study, we investigated the impact of small-molecule PKC inhibitors bisindolylmaleimide I (BIM) and sotrastaurin (AEB071), combined with ionizing radiation (IR), on survival in melanoma cell lines. METHODS: Cellular radiosensitivity was determined by using a combination of proliferation, viability, and clonogenic assays. Cell-cycle effects were measured by flow cytometry. Transcriptomic and proteomic profiling were performed by quantitative real-time PCR, reverse-phase protein array analysis, and immunofluorescence. RESULTS: We found that the PKC inhibitors combined with IR significantly decreased the viability, proliferation, and clonogenic potential of GNAQ(mt), but not GNAQ(wt)/BRAF(mt) cells, compared with IR alone. Combined treatment increased the antiproliferative and proapoptotic effects of IR in GNAQ(mt) cells through delayed DNA-damage resolution and enhanced induction of proteins involved in cell-cycle arrest, cell-growth arrest, and apoptosis. CONCLUSIONS: Our preclinical results suggest that combined modality treatment may allow for reductions in the total RT dose and/or fraction size, which may lead to better functional organ preservation in the treatment of primary GNAQ(mt) UM. These findings suggest future clinical trials combining PKC inhibitors with RT in GNAQ(mt) UM warrant consideration.