A 68-year-old man from rural Maharashtra presents with lower urinary tract symptoms (LUTS) and a 6-month history of progressive urinary hesitancy and nocturia (×4). Digital rectal examination (DRE) reveals a hard, irregular, fixed prostate nodule in the left lobe. Serum PSA is 28 ng/mL (normal <4 ng/mL). Transrectal ultrasound-guided biopsy confirms adenocarcinoma (Gleason score 8). Staging investigations show no distant metastases, but MRI pelvis reveals extraprostatic extension and involvement of the left seminal vesicle. What is the most appropriate initial management?