Prostate cancer incidence escalates dramatically with increasing age. Although it is a very unusual disease in men younger than 50 years, rates increase exponentially thereafter. The registration rate by age cohort in England and Wales increased from eight per thousand population in men aged 50 to 56 years to 68 per thousand in men aged 60 to 64 years; 260 per thousand in men aged 70 to 74 years, and peaked at 406 per thousand in men aged 75 to 79 years. In this same population, the death rate per thousand in 1992 in cohorts of men aged 50 to 54 years, 60 to 64 years, and 70 to 74 years was 4, 37, and 166, respectively. At all ages, incidence of prostate cancer in blacks exceeds those of whites.
Cancer of the hypopharynx is uncommon; approximately 2,500 new cases are diagnosed in the United States each year. The peak incidence of this cancer occurs in males and females aged 50 to 60 years. Excessive alcohol and tobacco use are the primary risk factors for hypopharyngeal cancer.[3,4] In the United States, hypopharyngeal cancers are more common in men than in women. In Europe and Asia, high incidences of pharyngeal cancers, namely, oropharyngeal and hypopharyngeal, have been found...
Approximately 15% of men with a diagnosis of prostate cancer will be found to have a first-degree male relative (e.g., brother, father) with prostate cancer, compared with approximately 8% of the U.S. population. Approximately 9% of all prostate cancers may result from heritable susceptibility genes. Several authors have completed segregation analyses, and though a single, rare autosomal gene has been suggested to cause cancer in some of these families, the burden of evidence suggests that the inheritance is considerably more complex.[5,6,7]
The development of the prostate is dependent upon the secretion of dihydrotestosterone (DHT) by the fetal testis. Testosterone causes normal virilization of the Wolffian duct structures and internal genitalia and is acted upon by the enzyme 5-alpha-reductase (5AR) to form DHT. DHT has a 4-fold to 50-fold greater affinity for the androgen receptor than testosterone, and it is DHT that leads to normal prostatic development. Children born with abnormal 5AR (due to a change in a single base pair in exon 5 of the normal type II 5AR gene), are born with ambiguous genitalia (variously described as hypospadias with a blind-ending vagina to a small phallus) but masculinize at puberty because of the surge of testosterone production at that time. Clinical, imaging, and histologic studies of kindreds born with 5AR deficiency have demonstrated a small, pancake-appearing prostate with an undetectable prostate-specific antigen (PSA) level and no evidence of prostatic epithelium. Long-term follow-up demonstrates that neither benign prostatic hyperplasia (BPH) nor prostate cancer develop.