Discussion
HNCs constitute a major public health concern worldwide. There has been
a significant increase in the global incidence of HNC, which is
increasing sharply in developing countries (1).
Studies from South America and West Africa have shown a similar burden
of disease (7-9). Limited data onthe epidemiological
trends of HNC in Southern Africa exist. The aim of the current study was
to describe the profile of HNC at a major referral public hospital (TBH,
Western Cape, South Africa) in Southern Africa. This information may
help to develop effective education and research efforts by local and
international non-governmental agencies to help reduce the mortalities
and morbidities associated with HNC.
854 patients were diagnosed with HNC between 2015 and 2017, representing
12.7% of all patients seen at the Radiation Oncology Department at TBH
during this period. The median age in this cohort was 58 years, with
most patients being between the ages of 51 and 70 years, similar to the
global age trend observed for tobacco-associated
HNC(5). Over 70% of patients were males, consistent
with the existing reports that men are two to three times more likely to
develop HNC (5). The male: female ratio was 2.4:1; and
globally this ratio varies between 2:1 to 4:1. (10)
The most predominate histologic type was SCC, which accounted for 791
(92.6%) of all HNC cases. Smoking was a risk factor in 737 of the
subjects (86.3%), and alcohol in 634 (74.2%). Both smoking and alcohol
were co-risk factors 72.6% (n=620) of the patients. Tobacco smoking and
alcohol consumption are well-established major risk factors for HNC and
a synergistic effect of these two factors has been consistently reported(11).
HR-HPV is an established risk factor for the development of
Oropharyngeal Squamous Cell Carcinoma (OPSCC). There is significant
geographic heterogeneity in the prevalence of HPV-positive OPSCC.
Of 167 patients with oropharyngeal primaries, 9.58% (n=16) had
p16-positive SCC.46.70% (n=78) were p16-negative and the p16 status was
unknown in 43.7% (n=73). Only 3 of the p16 positive OPSCC were HPV-DNA
positive, suggesting that p16 appears to have a low positive predictive
value in our setting, and may not be used as a standalone HPV test or a
surrogate marker for HR-HPV infection. Eleven of the patients with
p16-positive tumours had both smoking and alcohol as risk factors, and
it appears that mechanismsother than HR-HPV infection may be involved
(e.g. Rb mutation) in p16 overexpression.
A large number of oropharyngeal primaries (43.7%) had unknown HPV
status, due to the fact that p16 became a routine test for oropharyngeal
primaries at this hospital in recent years. Thus, we are unable to draw
conclusions about the overall prevalence of HPV-positive OPSCC at TBH
during the study period. However, given the very low incidence of true
HPV-positive cases in the cohort of OPSCC cases with known p16 status
(3/94=3.2%), it may be speculated that HR-HPV exposure is possibly not
a major risk factor for the development of OPSCC at this centre.
Indeed, the increasing incidence of HNC in Southern Africa is mostly due
to increasing smoking and drinking habits, and that preventative
strategies/campaigns should primarily target tobacco and alcohol
industries. Nevertheless, many countries in Africa are undergoing
economic modernization, resulting in major changes in lifestyle, diet
and sexual behaviour and in coming years we may observe an increasing
incidence of HPV-positive OPSCC.
Fifty-six (9%) patients were HIV positive, 721 (84%) were HIV negative
and 77 (7%) had unknown HIV status. The HIV prevalence in the Western
Cape was 12.6% in 2017(12). The South African
National HIV Prevalence, Incidence and Behaviour Survey in 2012 reported
an HIV prevalence of 7.6% in individuals over 50 years of age(12). The prevalence of HIV infection in our cohort of
patients with the median age of 58 years, is similar tothe nationwide
prevalence of 9% in patients over 50 years of age. It appears that HIV
infection plays a minor role in the development of HNC in South Africa.
The exact mechanism of HIV promoted carcinogenesis is not known(13).
According to the 2011 South African census, low-income households are
classified as those with a combined annual household income of below
R19200 ($1280). In this study, 56% of the patients fall into the
low-income category. Studies have shown an increased risk of HNC in
individuals of lower socioeconomic status, even after controlling for
other risk factors such as smoking and alcohol consumption(14,15). We can deduct from the latter that
comprehensive HNC control programmes should also address the social
inequalities and the high unemployment rate in Southern African
countries.
The most common anatomical site in this study was the oral cavity (320,
37%), followed by the larynx (188, 21.73%) and the oropharynx (167,
19.31%). The most common sub-site was the anterior tongue, accounting
for 15.84% (137) of the cases, followed by supraglottis 11.33% (98)
and the glottis 10.40% (90), in descending order of frequency. The
Surveillance, Epidemiology, and End Results [SEER] Programme reports
that the commonest site for HNC is the oral tongue followed by the
larynx (16).
Field cancerization describes the presence of premalignant fields
surrounding the primary tumour and has been related to the high rate of
local recurrence in HNC as well as the development of synchronous
primaries (17). Synchronous cancer is
defined as two or more neoplasms identified simultaneously in the same
patient. It is estimated that 1 to 6% of the patients
diagnosed with SCC of head and neck will have a synchronous primary in
the head and neck region (18). In this study eleven
patients (1.3%) presented with a synchronous primary in the head and
neck region.
According to the Surveillance, Epidemiology, and End Results (SEER)
database, in the United States 42-62% of patients with HNC presented
with locally advanced disease and 16-27% with distant
metastases(2). An epidemiological review of head and
neck patients at a university hospital in Brazil reported that 47.8% of
patients had T3/T4 disease and 31.9% had node positive disease(7). In the current study, a significant number of
patients presented with locally advanced disease (53.87%, n=466),
consistent with the data from the SEER database. The incidence of
distant metastases was 6.21%, which is lower than that of patients
presenting in the United States.
The treatment intent and modality offered to patients depends on
multiple factors, i.e. stage at presentation, performance status,
co-morbidities, social circumstances as well as patient wishes. In our
patient group, 449 (52.6%) patients had treatment with radical intent
and 405 (47.4%) with palliative intent. The majority of patients in the
radical intent group had surgery (72.4%) and approximately the same
proportion of patients received radiotherapy as part of their treatment.
226 patients (50.3%) received combined modality, including surgery,
chemotherapy and radiotherapy.
Of the patients that received palliative intent, 76.5% received
radiotherapy and 21.5% were not fit for any treatment and received
medical palliation and best supportive care. Just less than half of the
patients were for palliative intent; this could be due to the late stage
at presentation. The latter could be attributed to poor socio-economic
status, lack of knowledge and understanding, problems accessing health
services, cultural and religious beliefs, and possible other unknown
factors i.e. genetic factors in this patient population.