CU Dental 2018 - 22

The Changing Face of
Oropharyngeal Cancer:

Insights into Causation, Diagnosis and Treatment
ROBERT O GREER JR., DDS, SCD CU SCHOOL OF DENTAL MEDICINE

YOU SPOKE,
WE LISTENED!
Top Alumni Topic

Based on the 2017 CU Anschutz
Alumni Engagement Survey,
you chose oral pathology as the
top topic of interest. And we
just so happen to have a top
pathology expert right here at
the School of Dental Medicine.
Dr. Robert Greer is not only our
Chair of the Division of Oral and
Maxillofacial Pathology, he is also
an expert among his peers and
has published four pathology
textbooks. Awarded the inaugural
Excellence in Education Award
earlier this year, Dr. Greer has
taught oral and maxillofacial
pathology and clinical oncology
to every CU Dental class, save
for a 1987-1988 sabbatical year.
So for most of you, please enjoy
another pathology class from our
beloved, Dr. Greer.

22

CU DENTAL 2018

Causative Agents: Human
Papillomavirus, Tobacco,
Alcohol and Marijuana
Cancer of the oropharyngeal region,
once thought to be a relatively uniform
disease has proven to be anything but.
Over the past two decades, scientists
have demonstrated that squamous
epithelial cancers, the most common
form of cancer in the region represent
a heterogeneous group of diseases,
and thus, the long held contention that
alcohol abuse and/or tobacco exposure
are routinely and exclusively the causes
of oral squamous cancer has been
disproven. Recent research has shown
that as high as 30% of oropharyngeal
squamous cell carcinomas are caused
by
human
papillomavirus
(HPV)
infection. HPV associated oropharyngeal
cancer now appears to be escalating
in incidence. This finding overarches
the entire head and neck oncology
landscape as it dramatically impacts
diagnostic and therapeutic decisions.
Knowledge of a tumor's HPV status
has become a pathologic diagnostic
imperative in the reporting of all oral
pharyngeal squamous cancers. The
presence or absence of HPV infection,
along with documentation of the depth
of invasion of a neoplasm into the
connective tissue, rather than a tumor's
degree of differentiation, have become
standard of care mandates.
Although the typical patient with
oral cancer has long been an older male
who has smoked cigarettes and used
alcohol, this prototype is being seen less
often. The patients who are now being
diagnosed with oropharyngeal cancer
tend to be younger, more often in the
fourth and fifth decades of life; they are

increasingly female, and they are often
individuals with insidious multifocal oral
proliferative leukoplakia (PVL) (Figures
2a & 2b), who have never smoked or
used alcohol.
It is interesting to note that marijuana
use has recently been identified as a
risk factor for HPV-positive head and
neck squamous cell carcinoma and the
causal association between the two
increases with the intensity, duration
and cumulative years of marijuana
smoking. Although marijuana has long
been considered a potential source of
DNA damaging carcinogens, recent
investigations suggest that marijuana
smoke may be linked, more importantly,
on a causal level with its immune down
regulatory effects on the host.
Cannabinoids are known to bind
to the CB2, a protein-coupled receptor
that can be found on immune regulatory
cells in human tonsillar tissue. This
binding seems to suppress host immune
response, reduced host response to
viral pathogens, and in turn suppress
antitumor immune surveillance.

Figures 2a & 2b:
Proliferative verrucous leukoplakia



Table of Contents for the Digital Edition of CU Dental 2018

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CU Dental 2018 - Cover1
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