Instructor: Hi all.
In this lecture we'll be discussing
the epidemiology of penile cancer.
Our goals for this lecture are to describe the global burden
of penile cancer
and the global distribution of penile cancer.
We also will look at the pathogenesis, risk factors,
and prevention and control of this cancer.
So carcinoma of the penis is an uncommon
and potentially mutilating disease
with a heterogeneous etiology.
The malignancy is predominantly found in men
who are not circumcised shortly after birth
and is rarely found in populations
where neonatal circumcision is routine.
Sexually transmitted infectious agents
like Oncogenic Human Papilloma virus
may cause disease even in circumcised men.
There are approximately 26,000 new cases
of penile cancer diagnosed every year among males globally.
Carcinomas with the penis are rare
among men living in developed or high income countries
but are relatively common among the male populations
of some low and middle income countries.
Low annual incidents rates ranging from 0.3 to 1
per 100,000 are observed in high income countries
like the US, Canada, Great Britain, Australia, New Zealand,
and Western Europe and Scandinavian nations.
Rates are very low among Israeli Jewish men,
0.1 per 100,000 who are circumcised shortly after birth
and among Muslim men or 0.2 per 100,000
who are circumcised during childhood.
In contrast, rates are much higher,
3 to 10 per 100,000 among men living
in certain parts of the world where circumcision is rare.
Several high risk populations have been identified
in regions of Uganda, India, Thailand,
Puerto Rico, Paraguay, Brazil, and elsewhere
in which penile cancer accounts for 10 to 22%
of all malignancies in men.
Penile cancer is diagnosed predominantly in elderly men
although onset in young adult males does occur.
The median age of diagnosis of penile cancer
is about 68 years of age
and the incidence increases steadily
throughout life and rates are highest
for elderly men aged 70 years or older.
In 2020, there was an age standardized incidence of 0.8
per 100,000 men and a mortality of 0.29 per 100,000 men.
The vast majority, or over 95% of penile malignancies
are squamous cell carcinomas
that arise from the epithelium covering the organ.
Other rare forms include basal cell carcinoma, melanoma,
lymphoma, and sarcoma.
Squamous cell carcinomas of the penis
evolved through a stepwise process.
Over a period of several years,
early dysplastic lesions develop in procrast
to carcinomas and in situ.
Penile carcinoma in situ is called Bowen's disease,
Bowenoid papulosis, and Erythroplasia of Queyrat.
Cancer cells can breach the basement membrane
leading to invasive carcinoma,
which has the capability of disseminating to lymph nodes
and other tissues.
There's several key forms of penile cancer.
The first or rather forms or precursors to penile cancer.
The first, Lichen sclerosis is characterized
by white atrophic plaques on the glands
and pupus or the foreskin of the penis.
These plaques may enlarge and coalesce
to form sclerotic masses.
Uncircumcised men with Lichen sclerosis
are at markedly elevated risk
for the development of carcinoma of the penis.
Leukoplakia refers to the solitary or multiple
white scaly plaques often involving the glands or mitis.
Such lesions arise due to chronic irritation
and inflammation and are often found
in close proximity to squamous cell carcinomas.
Focal areas of dysplasia which can progress to cancer
are present in up to 20% of cases of penial leukoplakia.
Finally, Condyloma acuminata or genital warts
can arise on the penis as well as other intergenital sites
of both men and women.
These are usually benign
but malignant transformation has been observed
in association with oncogenic subtypes of HPV infection,
particularly HPV 16 and 18.
Poor genital hygiene, smegma retention, and phimosis
or unretractable foreskin are key risk factors
for penile cancer.
Infection of the genitalia by oncogenic strains
of human papilloma virus has been confirmed
to play an etiologic role in a subset of cases.
Penile rash, abrasion, urethral stricture,
and inflammation have also been found to increase the risk.
Chronic inflammation is a key component of tumor development
and progression, and most penile cancers arise at sites
of chronic infection, chronic irritation, or injury.
Multiple studies have found
that neonatal circumcision reduces the risk of carcinoma
in the penis by 60 to 70%.
Finally, although circumcision is controversial
a recent report from the American Academy of Pediatrics
concluded the health benefits of infant circumcision
outweigh the risks.
This figure shows the global prevalence of circumcision
by country.
Overall, about one third of all men have been circumcised.
Prevalence rates of circumcision are highest among Jewish
and Muslim men and men living in industrialized nations.
The incidence and mortality rates of penile cancer
tend to be lower in those countries
with higher prevalence rates of circumcision.
Phimosis refers to circumferential fibrosis
of preputial tissues or the foreskin in uncircumcised men
that leads to narrowing and inability to retract
the penile foreskin over the gland's penis.
This condition leads to the accumulation of smegma
beneath the foreskin and predisposes
to chronic inflammation and infection.
Fibrosis is found in about 1% of uncircumcised men
but rarely in circumcised men.
In a study of uncircumcised school boys
conducted in Denmark, the incidence of phimosis
among 3,355 adolescent boys aged 14 to 17 years was 1.1%.
Several studies have found that phimosis
among uncircumcised men is associated with
an approximate tenfold higher risk of penile cancer,
whereas uncircumcised men with no history of phimosis
are not at elevated risk.
Cancer of the scrotum was the first
documented malignancy arising from an occupational exposure.
In 1775, Percival Pott described
that the development of cancer of the scrotum
among chimney sweeps in England.
He called this tumor the "chimney sweeper's cancer"
and attributed the condition to a lodgement of scoot
in the reggae of the scrotum.
Finally, to discuss prevention and control of cancer
from the male genitalia.
Prevention strategies should target the major risk factors
for penile carcinoma, including phimosis
in uncircumcised men, promiscuous sexual activity,
infection with HPV 16, or other oncogenic strains
and cigarette smoking.
The WHO includes circumcision as a key component
of a comprehensive program for HIV control
in sub-Saharan Africa and other areas
with high endemic rates of HIV.
And other options include vaccination
against oncogenic HPV strains, condom use
to prevent virus transmission,
and health education to prevent smoking,
promote smoking cessation, and to improve genital hygiene.