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12 Testudo Vol. 8, No. 5
Characterisation of fibropapillomatosis
tumour growth profiles in green sea turtles
(Chelonia mydas)
Jessica Farrell1, Rachel Thomas1, Mark Q. Martindale1 and David J.
Duffy1,2,3
1 The Whitney Laboratory for Marine Bioscience and Sea Turtle
Hospital, University of Florida, St. Augustine, Florida 32080, USA
2 Molecular Ecology and Fisheries Genetics Laboratory, School of
Biological Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
3 Department of Biological Sciences, School of Natural Sciences,
Faculty of Science and Engineering, University of Limerick, Limerick,
Ireland
Email: duffy@whitney.ufl.edu
d.duffy@bangor.ac.uk
jessicafarrell@ufl.edu
Presented to the BCG Northern Symposium at Chester Zoo on 21st
October 2017
Background
Wild sea turtle populations are currently listed as threatened and endangered
as a result of both natural and anthropogenic factors (Jones et al. 2016;
Duffy et al. 2018; IUCN 2018). These include predation, disease, starvation,
pollution, fisheries interaction and habitat degradation. Many natural threats
including disease outbreaks have been exacerbated by human interaction
(Dos Santos et al. 2010; Jones et al. 2016; Whilde et al. 2017). One disease of
increasing threat to marine turtle populations worldwide is fibropapillomatosis
(FP), a virulent cancer (Fig. 1), thought to be triggered by a chelonian-specific
herpes virus, ChHV5 (Herbst et al. 1995; Jones et al. 2016; Work et al. 2017;
Morrison et al. 2018).
First reported in the scientific literature in 1938, FP prevalence was as low
as 1.5% in the Florida Keys at that time (Smith & Coates 1938). Eyewitness
sources suggest the first cases occurred as early as the late 1800s (Cruz
1985). Fibropapillomatosis did not reach epizootic proportions until the
1980s when a combination of increased coastal development and human-
induced climate change began to significantly degrade juvenile sea turtle
habitats. Presenting as single or several benign fibroepithelial cutaneous
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 13
lesions (Jones et al. 2016), the disease significantly affects turtle survivorship
once the tumours are of significant size in locations inhibiting vision, feeding,
internal organ function and locomotive ability. The disease progressed to
a panzootic in the 1990s with outbreaks in the eastern Pacific, Hawaiian
Islands, Indonesia and Australia (Duarte et al. 2012; Page-Karjian et al. 2014;
Hargrove et al. 2016; Jones et al. 2016). Currently, there are a number of
FP visual scoring systems including the fibropapillomatosis index (FPI) (Rossi
et al. 2016) and a four-category size classification which ranks the tumour
burden from 0 to 3 (Work & Balazs 1999).
The number of turtles stranding with FP in Florida has exploded in recent
years, with over 250 entering Florida rehabilitation facilities in 2017. This
trend is likely to continue into the future (Foley 2015; Hargrove et al. 2016;
Duffy et al. 2018). Reported in all seven marine turtle species, FP most
severely impacts green sea turtles (Chelonia mydas). Evidence suggests that
its geographic range is spreading to more northern latitudes where FP was
never previously recorded. The disease is now undermining conservation
efforts across the globe (Duarte et al. 2012; Page-Karjian et al. 2014;
Hargrove et al. 2016; Jones et al. 2016; Duffy et al. 2018).
Currently, the only commonly applied treatment for FP is surgery, which
is expensive, restricted to only a small number of turtle hospitals and 60%
of the time results in tumour regrowth post-surgery (Page-Karjian et al.
2014; Whilde et al. 2017). While the occurrence of FP tumours and post-
surgical regrowth has been recorded previously, the specific growth rates
of tumours pre- and post-surgery have never been assessed in detail. Such
data are vital for establishing a growth baseline to better understand the
disease and factors that may be accelerating its growth. Additionally, tumour
growth baselines are crucial when assessing the effectiveness of targeted
therapeutics. Once baseline FP tumour growth rates are established, these
can be used to compare the rate of tumour growth and regrowth in
patients subjected to various candidate drug treatments in order to identify
the most effective course of treatment for FP-afflicted patients. Innovative
treatment approaches are vital to help maintain healthy marine populations
until the chronic underlying causes of these diseases can be addressed and
preventative measures can be enforced (Duffy et al. 2018).
Objectives
This paper documents the growth and post-surgical regrowth rates of FP
tumours in four C. mydas patients at the University of Florida’s Whitney Sea
Turtle Hospital. These data will indicate which tumour locations are more
susceptible to accelerated tumour regrowth. The results will also be useful as
baseline information for future drug treatment studies, as well as suggesting
further beneficial refinements to tumour growth profiling techniques.
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
14 Testudo Vol. 8, No. 5
Method
Sample population: This study used existing images, taken as part of the
rehabilitative care of four juvenile C. mydas patients admitted to the Whitney
Sea Turtle Hospital between September 2016 and April 2017. Images were
taken using an Olympus Tough TG-4 approximately 30cm from each lesion,
with a 25cm scale bar for accurate pixel comparison. All four patients were
found stranded along the east coast of Florida between Anastasia State
Park (north, 29.9083°N, 81.2837°W) and Ponce Inlet (south, 29.0779°N,
80.9211°W), displaying fibropapilloma-like tumours. Each patient received
medical care devised to best suit their particular circumstances; thus the
number of surgeries and duration of tumour growth analysis varies for each
turtle. The outcome of each patient differs, with some determined healthy
enough for release and others requiring euthanasia and necropsy. Tumour
removal surgeries involved the use of a CO2 laser to excise tumours and
cauterize surgical incision sites.
Table 1. Carapace length, weight, origin, condition on arrival and FP tumour scores of green
sea turtles (C. mydas) observed during this study at the Whitney Laboratory for Marine
Bioscience Sea Turtle Hospital.
Patient
ID
Straight
carapace length
(upon admittance)
cm
Weight
(upon admittance)
kg
Origin Condition
on arrival
FP tumour score
(FPI)
(Rossi et al.
2016)
Chrystal 29.2 2.8 Volusia FL Normal body
condition, FP
>66.5
Tamatoa 33.6 4.6 St. Johns
FL
Normal body
condition, FP
22.1
Pons 42.8 7.5 Volusia FL Emaciated, FP >6.5
Remi 35.7 3.8 Volusia FL Emaciated, FP >205.6
Image analysis: ImageJ is an image processing programme designed for
scientific multidimensional images (https://imagej.nih.gov/ij). Image analysis
using this computer software allows accurate measurements of tumour two-
dimensional surface area. It should be noted that the surface measurements
used in this study serve as a proxy for overall tumour growth. In future studies,
physical measurements of the three-dimensional tumour structures will allow
a more in-depth direct assessment of tumour growth dynamics. However, here
we evaluated the use of ImageJ software to track tumour growth. Existing
historical FP patient datasets primarily only contain visual records of tumour
growth, so, if found to be an applicable approach, two-dimensional surface
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 15
Fig. 1. Location of designated FP tumour ‘clusters’ on green sea turtle anatomy
(Patient 4: Remi).
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
16 Testudo Vol. 8, No. 5
area measurement would then be retroactively applicable to a large cohort
of patient data. Each tumour is assigned to a ‘cluster’ to enable analysis of
tumour growth in designated locations on the turtle anatomy (Fig. 1 and
Table 2). Each cluster was photographed by a member of the Whitney Sea
Turtle Hospital veterinary team on arrival, at each check-up and after each
surgery. These images were analysed in ImageJ in order to plot the growth
(surface area) and post-surgical regrowth of each cluster.
Table 2. Body location and abbreviations of tumour clusters used in this study.
Location designated as tumour clusters Cluster abbreviation Figure 1 Cluster location
number
Left Eye LEy 1
Right Eye REy 2
Dorsal Neck DNk 3
Ventral Neck VNk 4
Carapace Carapace 5
Plastron Plastron 6
Left Front Flipper Base LFFBa 7
Left Front Flipper Along LFFAl 8
Right Front Flipper Base RFFBa 9
Right Front Flipper Along RFFAl 10
Left Rear Flipper Base LRFBa 11
Left Rear Flipper Along LRFAl 12
Right Rear Flipper Base RRFBa 13
Right Rear Flipper Along RRFAl 14
Tail Tail 15
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 17
Results
Patient summaries
PATIENT 1: CHRYSTAL
Chrystal was first photographed at the Whitney Sea Turtle Hospital on January
12th 2017 (Fig. 2A). She underwent three surgeries to mitigate the severity
of her fibropapillomatosis burden. Photographs were taken after each of
Chrystal’s surgeries on the following dates:
RFebruary 8th: removal of tumours from Left Eye (LEy), Right Eye (REy),
Right Rear Flipper Base (RRFBa) and Left Front Flipper Base (LFFBa).
RMay 1st: removal of tumours from Right Front Flipper Base (RFFBa) and
Right Front Flipper Along (RRFAl).
RJune 13th: removal of tumours from LEy and REy (for the second time)
and Dorsal Neck (DNk).
The most persistent tumour regrowth was seen on Chrystal’s eyes (Fig. 2B
& Table 3). Limited regrowth was seen on the RFFBa and RFFAl (Fig. 2B).
No regrowth was seen on the LFFBa. All clusters left untreated by surgery
showed continuous steady growth. Due to continual tumour regrowth and
the diagnosis of internal lung tumours and impacts on quality of life, Chrystal
was euthanised on August 9th 2017, after 210 days in rehab, with a thorough
necropsy providing evidence of significant internal FP tumour growth – in
particular, a large golf ball-sized tumour located within the shoulder of the
RFFBa. The necropsy determined that Chrystal was a female.
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
18 Testudo Vol. 8, No. 5
Fig. 2. Fibropapillomatosis in a green turtle (Patient 1: Chrystal).
(A) Chrystal’s initial intake photograph upon admittance to the hospital.
(B) Growth profile of selected FP tumour clusters on Chrystal.
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 19
PATIENT 2: TAMATOA
Tamatoa was admitted to the Whitney Sea Turtle Hospital on April 17th 2017
(Fig. 3A), after stranding at Anastasia State Park, Florida.
RTamatoa underwent one surgery on May 15th 2017 to remove tumours
from its RFFBa, LFFBa and RRFBa.
Tamatoa showed no signs of tumour regrowth post-surgery (Fig. 3B & Table 3).
Showing good health and no indication of regrowth, Tamatoa was released
on July 13th 2017, after 88 days in rehab. Tamatoa was subsequently found
re-stranded and alive on August 27th 2017 at Anastasia State Park as a result
of being caught in a cast-net. There was no indication of FP tumours.
Fig. 3. Patient 2: Tamatoa. (A) Tamatoa’s initial intake photograph upon admittance to the
hospital. Tamatoa was found stranded by the Salt Run fish cleaning table in Anastasia State
Park, where he was habitually fed by local fishermen. (B) Growth profile of the surface area of
Tamatoa’s RFFBa cluster, obstructed in (A) due to placement of flipper.
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
20 Testudo Vol. 8, No. 5
PATIENT 3: PONS
Pons was reported as stranded to the Whitney Sea Turtle Hospital on September
25th 2016 and was collected from the water at Ponce Inlet, Florida. Pons was
first photographed at the Whitney Sea Turtle Hospital on October 4th 2016
(Fig. 4A). Pons was thin, with a healed propeller wound to the first vertebral
and left costal, and minimal algae and barnacles on the carapace.
RPons underwent one surgery on December 14th 2017 to remove
tumours from its LFFBa, RFFBa, LRFBa, RRFBa and Tail.
Pons showed the start of very minor regrowth on the LFFBa, RRFBa and Tail
(Fig. 4B). No regrowth was seen on the RFFBa or LRFBa. Showing good health
and no further regrowth, Pons was released on March 16th 2017, after 173
days in rehab. Pons was subsequently caught and released by a fisherman on
March 28th 2017; however, there was no indication of FP tumours, suggesting
that the beginnings of regrowth regressed while in the wild.
Fig. 4. Patient 3: Pons.
(A) Pon’s initial intake photograph upon admittance to the hospital. Found floating in Ponce
Inlet, Volusia County, with monofilament tangled around the right rear flipper base.
(B) Growth profile of selected FP tumour clusters on Pons.
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 21
Fig. 5. Patient 4: Remi.
(A) Remi’s initial intake photograph upon admittance to the hospital. Remi was found
and collected from the inshore waters of South Daytona Beach Canal off the Halifax River,
underweight and lacking in energy.
(B) Growth profile of selected FP tumour clusters on Remi.
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
22 Testudo Vol. 8, No. 5
PATIENT 4: REMI
Remi was reported as stranded to the Whitney Sea Turtle Hospital on April 10th
2017 and was collected from the inshore waters of Halifax River, Florida. Remi was
first photographed at the Whitney Sea Turtle Hospital on April 10th 2017 (Fig. 5A).
Remi was thin and lethargic with mud and algae covering his carapace. The patient
underwent four surgeries to mitigate the severity of its FP burden. Photographs
were taken after each of Remi’s surgeries on the following dates in 2017:
RMay 1st: removal of tumours from Carapace, RFFAl, RFFBa and Plastron.
RMay 30th: removal of tumours from LEy.
RJune 28th: removal of tumours from LFFAl, LFFBa, LRFBa and LRFAl.
RJuly 26th: removal of tumours from RRFBa, RRFAl, LEy (for the second time),
Ventral Neck (VNk) and Plastron (for the second time).
The most persistent tumour regrowth was seen on Remi’s left eye (LEy) as well as
the Plastron (Fig. 5B). Minor regrowth was seen on the LFFBa (Fig. 5B). No regrowth
was seen on the Carapace, VNk, RFFBa, RFFAl, LFFAl, LRFBa, LRFAl, RRFBa and
RRFAl. Due to its multiple surgeries and continued regrowth Remi remained in the
care of the Whitney Sea Turtle Hospital for a total of 344 days, but was successfully
released on 20th March 2018.
Tumour growth rates by individual and cluster locations
We assessed the growth rates of all tumour clusters, examining whether there
was any correlation in cluster location and the pre-surgery growth rate, across all
four patients. Generally, plastron tumours and those at the base of the flippers
tended to grow at a faster rate than other locations (Fig. 6A), although it should
be noted that these clusters also tended to have the largest tumour burdens (Table
3). Regrowth data were not available for some of Chrystal’s FP clusters, as surgery
took place too soon after the first photograph to have a second image available
(Table 3).
We next compared the predicted doubling time of each tumour (start size/pre-
surgery growth rate). Doubling time represents the hypothetical time it would
take (in days) for a tumour to double its original size (size at commencement of
measuring), assuming it continued to grow at its pre-surgery rate. While there
was a slight trend for larger tumours to require a longer doubling time (Fig. 6B),
despite their more rapid growth rate (Table 3), there was no strong correlation
between the size of a tumour and its predicted doubling time (linear correlation,
R2 = 0.01296).
In addition to characterising tumour growth rates as a baseline for future studies,
we also investigated whether there was any prognostic value in the pre-surgery
growth rates in terms of predicting patient outcome or the occurrence of post-
surgery tumour regrowth. However, the average tumour regrowth across all clusters
of an individual turtle were not predictive of rehabilitation outcome (Fig. 6C).
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 23
Fig. 6. Analysis of tumour growth rates.
(A) Average pre-surgery tumour growth rates combined by cluster, across all four patients.
(B) Predicted tumour doubling time by tumour starting size. Doubling time represents the
hypothetical time it would take (in days) for a tumour to double its original size, assuming it
had been allowed to continue to grow and maintained its pre-surgery growth rate.
(C) Average pre-surgery tumour growth rates combined by individual patient, related to
rehabilitation outcome.
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
24 Testudo Vol. 8, No. 5
Next we examined whether any of the tumours’ growth characteristics
(starting size, growth rate or growth rate/starting size) were predictive of the
occurrence of post-surgery regrowth (Fig. 7A). Interestingly, for those tumour
clusters with growth rate data available, the pre-surgery growth rate did not
clearly indicate whether a tumour would regrow post-surgery (Fig. 7A, B).
Fig. 7. Correlation of pre-surgery growth dynamics with the occurrence of post-surgical FP
tumour regrowth.
(A) Average pre-surgery tumour growth rates (left), tumour starting size (right) and growth
rate/starting size (bottom), across all patients and clusters (for which regrowth information
existed) grouped according to the occurrence of post-surgical tumour regrowth. Error bars
denote standard error.
(B) Tumour growth rate/starting size across patient clusters, grouped according to the
occurrence of post-surgical tumour regrowth.
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 25
Neither starting size (t-test, p = 0.6382, d.f. = 21), growth rate (t-test, p =
0.7050, d.f. = 21) or growth rate/starting size (t-test, p = 0.3931, d.f. = 21)
were significantly different between clusters exhibiting regrowth and those
having no post-surgery regrowth.
It should be noted that the negative growth rate for Chrystal’s REy cluster
was as a result of initial inflammation in that tumour being reduced upon
commencement of rehabilitative care. The reduction in size was not due to
genuine natural tumour regression. This inflammation complication also tallies
with the occurrence of post-surgical tumour regrowth in this eye. However,
even if this cluster is excluded from the analysis there remains no significant
difference between the no regrowth and regrowth clusters (t-test for growth
rate p = 0.4925, d.f. = 20, t-test for rate/starting size, p = 0.9634, d.f. =
20). Given this lack of significance we can rule out the use of these growth
characteristics as prognostic markers of tumour regrowth. However, reassessing
these features with a larger sample size would of course be highly desirable.
Discussion
Patients 2 and 3 received one surgery only as their symptoms were far less
advanced than Patients 1 and 4. As their FP was less advanced, they showed
minor or no regrowth and were released back into their wild populations.
Coincidentally, both patients were caught alive and released by fishermen
approximately one month later; however, there was no evidence of tumour
regrowth. As the patients were tagged, the fishermen took photos prior to
release to send to the hospital so as to keep track of patient health and
location.
Patients 1 and 4 displayed far more severe FP symptoms. Despite multiple
rounds of surgery, persistent tumour regrowth was a recurring problem.
The most susceptible sites requiring multiple surgeries were the eyes and
the plastron. Therefore, these sites should receive special focus in any
future adjunct post-surgery drug treatment trials. Due to the severity of
their symptoms, Patient 1 required euthanasia and Patient 4 remained in
rehabilitation almost one year after its initial stranding. Patient 1 displayed
continuous tumour regrowth and poor health. Her necropsy subsequently
showed extensive growth of internal FP tumours.
The two smallest patients, Chrystal and Remi (Table 1), were those most
affected by post-surgical tumour regrowth. Our observation supports the
findings made by Page-Karjian et al. (2014) that smaller turtles (straight
carapace lengths 30-35cm) were the most susceptible to FP tumour
development while in rehabilitation. Page-Karjian et al. (2014) suggested that
turtles are more likely to develop FP tumours during warmer rehabilitation
months (April-September), an observation also postulated elsewhere (Cruz
1985; Herbst et al. 1995; Jones et al. 2016; Duffy et al. 2018). This association
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
26 Testudo Vol. 8, No. 5
between warmer months and higher regrowth rates was also apparent with
both Patients 1 and 4 in this study. The most commonly FP-afflicted body
locations are stated to be the R/LFFBa, R/LFFAl, Tail, Plastron and R/LEy (Page-
Karjian et al. 2014). Again, the patients in this study support this finding. The
presence of ocular tumours can be a good indication of the outcome of the
Table 3. Pre-surgery fibropapillomatosis tumour growth characteristics and post-surgery
regrowth rates.
Patient Cluster Start Size
(mm2)
Growth Rate
Prior To
Surgical Removal
(mm2 per day)
Growth
Rate/
Start
Size
Re-Growth
Y/N
Growth
Period
(Days)
1. Chrystal Left Eye 460 7.0 0.016 Y11
Right Eye 485 -17.0 -0.035 Y11
Dorsal Neck 651 13.0 0.021 N138
Ventral Neck 1476 18.0 0.012 N/A 209
Plastron 447 23.0 0.053 N/A 209
Left Front Base 3662 3.0 0.001 N11
Left Front Along 202 15.0 0.076 N/A 209
Right Front Base 6234 94.0 0.015 Y95
Right Front Along 564 10.0 0.019 Y95
Left Rear Base 2111 48.0 0.023 N/A 209
Left Rear Along 43 1.0 0.024 N/A 209
Right Rear Base 7134 100.0 0.014 Y11
Tail 185 15.0 0.081 N/A 209
2. Tamatoa Left Front Base 1232 12.0 0.010 N14
Right Front Base 50 0.2 0.004 N14
Right Rear Base 1806 81.0 0.045 N14
3. Pons Left Front Base 341 3.0 0.010 Y71
Right Front Base 616 5.0 0.010 N71
Left Rear Base 1964 19.0 0.010 N71
Right Rear Base 1143 13.0 0.012 Y71
Tail 268 3.0 0.012 Y71
4. Remi Left Eye 60.03 0.004 Y35
Ventral Neck 78 0.6 0.007 N88
Carapace 1981 N/A N/A N21
Plastron 9903 N/A N/A Y21
Left Front Base 561 4.0 0.007 Y64
Left Front Along 421 8.0 0.021 N64
Right Front Base 1282 N/A N/A N21
Right Front Along 528 N/A N/A N21
Left Rear Base 3738 48.0 0.013 N64
Left Rear Along 1270 14.0 0.011 N64
Right Rear Base 1316 9.0 0.008 N88
Right Rear Along 446 0.5 0.001 N88
© British Chelonia Group + Jessica Farrell, ~Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
Testudo Vol. 8, No. 5 27
patient, as turtles without FP lesions on the eye are eight times more likely to
survive (Page-Karjian et al. 2014). The results from this study also support this
suggestion, as those turtles without eye tumours were able to be released,
while those with eye tumours required euthanasia or prolonged rehabilitation
time and medical care. In previous studies, the number of tumour removal
surgeries has not significantly related to patient outcome (Page-Karjian et
al. 2014). However, in this study a greater number of surgeries did coincide
with worse outcomes (euthanasia, extended rehabilitation time). In previous
studies, 38.5% of turtles experienced post-surgical regrowth within an average
of 36 days (Page-Karjian et al. 2014). In line with this, in our current study
50% of turtles experienced FP regrowth within 40 days. Of the 33 tumour
clusters surgically removed from these 4 patients, one third resulted in tumour
regrowth. This is slightly less than the 60% tumour regrowth observed in
previous studies (Page-Karjian et al. 2014).
The growth measurement protocol adopted in this study can be further
improved for future research in order to increase its accuracy and the level
of detailed analysis which is possible. Photos could be taken at a fixed
distance and at a consistent angle for each tumour cluster, and physical
measurements using callipers could be used to record accurate tumour
dimensions. While providing more precise data, these physical methods,
however, are considerably more time-consuming. Thus they are less likely to
be broadly adopted across many rehabilitation facilities, which are generally
time- and resource-limited.
Interestingly, this study suggests that the aggressiveness of the pre-surgery
growth rates do not have a bearing on the occurrence of post-surgery
tumour regrowth rates. Therefore, regrowth may be driven predominantly
by other factors such as inherent genetic/viral features of each tumour,
or tumour cells/tumour stem cells remaining in the body site post-surgery
(deeper surgical margins may alleviate this, although these are not possible
in some locations such as the eye). In line with the potential drivers of FP
regrowth, we have recently shown that adjunct post-surgery treatment with
the anti-cancer drug fluorouracil can help to dramatically reduce FP eye
tumour regrowth (Duffy et al. 2018).
The analysis of tumour growth in these four patients provides a useful
baseline with which to compare FP tumour growth rates in C. mydas
given novel FP treatments. Future studies can compare this baseline with
growth post-candidate drug treatment. Additionally, these data will provide
useful baseline information for studies investigating the effect of potential
environmental aggravators of FP tumour growth, such as UV exposure
and pollutant exposure (Keller et al. 2014; Jones et al. 2016; Duffy et al.
2018). If growth and regrowth rates can be reduced from the baseline rates
indicated in this study, it could eliminate the need for multiple rounds of
© British Chelonia Group + Jessica Farrell, Rachel
Thomas, Mark Q. Martindale and David J. Duffy,
2018
28 Testudo Vol. 8, No. 5
surgery, consequently decreasing the stress on the patient and increasing
their chances of successful re-introduction to their wild population. At a time
when anthropogenic factors are accelerating disease emergence and species
extinction (Whilde et al. 2017), it is vital to not only expand our scientific
understanding of the mechanics of diseases such as fibropapillomatosis,
but to use the knowledge gained to improve the care and recovery of
endangered animal populations.
Acknowledgements
Funding was generously provided by a grant awarded from the Sea Turtle
Grants Program, project number 17-033R, which is funded from proceeds from
the sale of the Florida Sea Turtle License Plate (www.helpingseaturtles.org) and
administered by The Sea Turtle Conservancy, by the Save Our Seas Foundation
under project number SOSF 356, and by a Welsh Government Sêr Cymru II
and the European Union’s Horizon 2020 research and innovation programme
under the Marie Skłodowska-Curie grant agreement No. 663830-BU115.
This research was also supported by Gumbo Limbo Nature Center, Inc d/b/a
Friends of Gumbo Limbo (a 501c3 non-profit organization) through a generous
donation through their Graduate Research Grant programme. Warmest thanks
are due to Catherine Eastman, Dr Brooke Burkhalter, Devon Rollinson, Dr Jenny
Whilde, the volunteers of UF’s Sea Turtle Hospital at the Whitney Laboratory
and to Nancy Condron and the Mickler’s Landing Sea Turtle Patrol.
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2018
