Radiation Oncology/Testis/Overview

Testes Overview Epidemiology 7000 cases/yr. Most common neoplasm in men ages 15-35. Highest incidence among white males especially from northern Europe. ~2/3 are clinical Stage I Most common testicular cancer in men >50 is lymphoma GCTs sometimes present in extragonadal sites: mediastinum, brain and sacrococcygeal region (often midline) Anatomy Surrounded by tunica albuginea Seminiferous tubules lead to rete testis, epididymis, vas efferens and finally to urethra Seminiferous tubules Spermatogonia participate in sperm production (~67 days) Sertoli cells are epithelial cells lining seminiferous tubules Nurture and support the developing sperm cells through the stages of spermatogenesis Produce several hormones, including estradiol to regulate spermatogenesis and androgen-binding protein to transport androgens Form blood-testis barrier Leydig cells are interstitial cells Responsible for endocrine function, primarily via production of testosterone Controlled by LH (testosterone synthesis) and FSH (increase in number of LH receptors) Rete testis = anastamosing network of tubules in the testicular hilum; sperm are concentrated Epididymis = sperm maturation and storage Natural history 10% of germ cell tumors may arise in non-gonadal sites, in which case it is usually an anterior mediastinal mass (as opposed to a posterior mediastinal mass, which is usually metastatic) or centrally located retroperitoneal (as opposed to lateralized masses seen in metastatic disease) Risk Factors Testicular abnormalities Cryptorchism Testicular atrophy Infertility Genetic abnormalities cKIT mutation is associated with bilateral testicular germ cell tumors Pathology 95% are germ cell tumors (Percentages taken from Ulbright TM, Amin MB, Young RH. Tumors of the testis, adnexa, spermatic cord, and scrotum. Atlas of tumor pathology. 3rd series. Fascicle 25. Washington, DC: Armed Forces Institute of Pathology, 1999.) Germ cell: Seminoma (50%) Non-seminoma (50%) Pure (15%): Embryonal (10%), teratoma (3-5%), choriocarcinoma (<1%), yolk-sac tumor (<1%) Mixed (35%) Sex-cord stroma: Leydig cell, Sertoli cell, granulosa cell Lymphoma: Common in men > 50 If the tumor has any component of a non-seminoma, it should be classified as a non-seminoma. If there is an elevated AFP even if the histology shows a pure seminoma, it should be classified as a non-seminoma. Seminoma - no differentiation; retains some aspects of spermatogenesis NSGCT - undergo some differentiation to totipotential cells Embryonic tissue differentiation - embryonal carcinoma and teratoma Extra-embryonic tissue differentiation - choriocarcinoma and yolk sac tumors Teratoma is not sensitive to chemotherapy. Requires resection. Does not metastasize. Choriocarcinoma is one of few tumors that metastasize more frequently hematogenously (also follicular carcinoma of the thyroid, renal cell carcinoma) Tumor markers Check AFP, B-HCG, and LDH. AFP - yolk sac, embryonal. Half-life is 5-7 days. Elevated in 70% of patients with teratocarcinomas and embryonal carcinomas. Never elevated in Seminomas B-HCG - choriocarcinoma, embryonal. Half-life is 18-36 hrs. Elevated in 40-60% of nonseminomas and ~10% of seminomas Placental Alk Phos - most sensitive for surveillance of pure seminomas with ~50% sensitivity for metastatic disease LDH - Surveillance marker with slight rise in ~80% of advanced seminomas and 60% of nonseminomas 1 in 5 pts with pure seminoma will have minimal B-HCG elevation (<100 mIU/mL). Tumor markers not elevated in pure teratomas. Prognostic factors Risk stratification: Tumors can be classified as good risk, intermediate risk, or poor risk using the IGCCCG system. For details see at Seminoma or Non-seminoma Radiation technique Para-aortic field borders - Designed to cover the potential drainage areas of the para-aortic region, remember testicular vein returns at L2. Top border - At or near the crura of the diaphram to cover insertions of the renal vein and antegrade flow Inferior border - Bifurcation of the common iliacs Lateral borders- Transverse processes of the vertebral bodies to cover LNs. Keep in mind L renal hilum. Toxicity For risk of second malignancies, please see the second malignancies page Review Erasmus, 2006 (Netherlands) PMID 17158533 -- "Controversies in the management of clinical stage I testis cancer." (de Wit R, J Clin Oncol. 2006 Dec 10;24(35):5482-92.) References