Screening results
Both groups identified as having a history of skin cancer (surfers
41.4% vs swimmers 36.4%, respectively) and a family history of skin
cancer (surfers 52.6% vs swimmers 43.6%). The majority of surfers and
swimmers that experienced blistering sunburns as a child were
significantly (P <0.05) more likely found to have at least one
skin cancer (BCC, SCC, SCC in situ, MSC; 74.1% vs 69.0%) identified in
this study than those who did not experience blistering sunburns as
children. Surfers reported a significantly higher (+85.5%, P
<.05) number of lesions of concern as compared to swimmers
prior to the screening.
There was no difference (P >.05) in experience (years
surfing or years swimming) between groups however, there was a
significant relationship between surfing experience (yrs) and the number
of skin cancers identified (r= 0.312, P <.001). There was no
difference in surfing or swimming total exposure hours and the number of
skin cancers (r=-0.126,; r=0.065, respectively). However, when groups
were combined, there were more participants identified with skin cancers
when investigating total aquatic activity exposure (Figure 1 (A),
quartile 1 vs quartile 4). Likewise, with groups combined, there were
more skin cancers identified with increased activity exposure (quartile
1 vs quartile 4, Figure 1 (B)).
Insert Figure 1 A and B approximately here
A total of 74 AKs were identified during the screening (surfers 59,
swimmers 15) and 110 skin cancers (BCC, SCC, SCC in situ, MSC) (Table
3). A significantly (P <.005) greater number of surfers were
identified with a skin lesion (PSC, NMSC, MSC) during the screening than
swimmers (132 vs 52, respectively; OR 1.85, 95%CI 1.0 to 3.5). Surfers
also had a higher number (P >.05) of AK and rate (per
100,000) compared to swimmers (50,862 vs 27,273 respectively, OR 2.76).
Surfers also had a higher number of BCCs compared to swimmers (27,568 vs
18,181 respectively, OR 1.71). Conversely, swimmers had a higher rate of
SCC in situ (20,6903 vs 40,000, OR 0.70). Surfers had a significantly (P
<.05) higher number of SCCs and a higher rate of SCCs compared
to swimmers (9,482 vs 7,272, OR 1.34). With regard to malignant
melanomas, surfers had a higher rate as compared to the swimmers (5,172
vs 1,818, OR 2.95).
When compared to the Australian general population, surfers and swimmers
had higher ORs, which includes BCCs (OR 17.9 and 11.8, respectively),
SCCs (OR 9.2 and 7.0, respectively) and MSC (OR 96.7 and 34.0,
respectively) (Table 4). .
A MANCOVA demonstrated statistically significant differences in skin
cancer totals (total number of skin cancers, total AKs, BCCs, SCC, SCC
in situ, melanoma) based upon history of skin cancer (F = 3.98, Pillai’s
Trace = 1.40, P <.001) with history of skin cancer as a fixed
factor and covariates of Fitzpatrick skin type and age. Adjusting the
mean number of skin cancers observed for covariates (age and Fitzpatrick
skin type), totals were higher for those with a history of skin cancer
(mean with skin cancer history 7.24 vs. 3.95 with no skin cancer
history, P =.012). A similar trend was observed for AKs (6.03 vs. 3.69,
NS), total BCC (0.66 vs. 0.06, P =.001), total SCC in situ (0.50 vs.
0.101, P=.042), total melanoma (0.62 vs. 0.44, NS) and total SCC (0.04
vs -0.01, P =.024, with the negative mean value due to adjustment to the
mean by covariates).
Most skin cancers in surfers were located on the face (28.0%) followed
by the arm and back (12.1% each), whereas in swimmers, the majority of
skin cancers were identified on the face (17.3%), followed by the arm
and lower leg (15.4% each). The highest number of melanomas were
identified in surfers (n=6) and mainly located on the face (n=2) and
back (n=2). There was a single melanoma identified on the back in a
swimmer. When the groups combined, the majority (42.9%) of melanomas
were identified on the back in participants, followed by the face
(28.6%) (Table 3).
A total of 110 samples were sent for histopathology, and all (100%)
were confirmed positive as either NMSC (BCC, SCC, SCC in situ) or MSC.