Cancer in amphibians is considered to be an extremely rare event. However, four cases were found by CSIRO several years ago during their chytrid testing of hundreds of frogs from eastern Australia. Not intending to outdo the rest of the country, Cairns has the dubious distinction of already having confirmed at least a dozen cases of squamous cell carcinoma (skin cancer) in local frogs (these are in addition to what CSIRO has found) and, more recently, at least one case of adenocarcinoma and a possibly world's first case of osteosarcoma in a frog.
Unfortunately, other tumours have also turned up. A biopsy of a growth on a rainforest frog's back was found to contain melanin but no futher determination was made as to if and what type of cancer it might be. From 2000 to 2002, four frogs were turned in with growths which have been identified as "epidermal papillomas" or benign tumours (see photos at right and below). However, just in the period from April to June 2003, we received another five cases of this type of growth. Two of these had both the papilloma type growth and another which was different again and definitely not nasopharyngeal squamous cell. We missed the opportunity to test the first frog sporting this new unobtrusive growth type but the second from (from Trinity Beach) was biopsied and the results have just come back (January 5th, 2004) as adenocarcinoma - a highly malignant cancer. This confirmed case appeared to be exactly the same tumour type as the previous case which was untested so it is possible we have received two cases of sebaceous adenocarcinoma.
Another type of tumour was present in two cases that came in just after cyclone Yasi passed through on February 3rd, 2011. Both cases were Litoria caerulea and both tumours were circular, about 1cm in diametre and just under the skin with an exposed patch where the skin was retreating. In view of our past experiences with soem of the cancer cases that had been sent to "credible" labs, we opted not to bother sending these. We could have sent them to the commercial vet lab but we weren't receiving enough financial support to afford that.
We have also received a case (Litoria caerulea) from Biboora (Mareeba region) which had multiple growths in its mouth. These were treated for parasites and protozoa to eliminate those as possibilities and treated with antibiotic in case they were bacterial absesses. None of the treatments worked and the growths actually enlarged to the extent that the frog could no longer swallow food. It was euthanaised. We would have preferred to send it to the commerical vet lab but couldn't afford it.
The number of cancer cases we are getting is extremely disconcerting. First impressions might be that the skin cancer cases are the result of the powerful sun exposure here in the tropics but this is not the 'best guess'. Chronic infections can also lead eventually to cancer but this is still not the 'best guess'. Another theory proposed to us which makes a lot more sense is the excessive level of chemicals in this region (used by everybody from households to councils to agriculture).
The squamous cell tumours we have seen on twelve of these frogs are called nasopharyngeal squamous cell carcinoma and this particular type of tumour is very common in people in China. In that country, that cancer is caused by a virus! Two different viruses have been implicated there: Epstein Barr Virus (which is common around the world) and one of the Papilloma (herpes) group of viruses. We have provided the tissues of this type to a virus researcher but the tissues became damaged in a power outage. Another lab (in TAS) had a look at the fifth case of this type (from Gordonvale) and reported that the tumour tissues were entirely consistent with papilloma induced growths.
Adenocarcinoma has been found in the Leopard frog (Rana pipiens) in the USA and Dr. Debra Carlson has been researching the virus that causes this particular cancer known as Lucke's rhenal adenocarcinoma. She discovered a herpes virus as the cause. The cancer cases here in Cairns are likely to be viral as well. Most of the cancer cases we have received are from a very specific part of Cairns, that being the northern beaches. But cases are popping up from other areas over the years including White Rock, Gordonvale, areas around Innisfail, and Port Douglas. Because so little frog work has been done on amphibian health problems outside of chytrid fungus, we don't know if there were any cases prior to our start up in August 1998. This might be a very recent problem tied to the approval of newer chemicals.
Another possible coincidence to these cases stems from the reference above to a particular type of squamous cell carcinoma being common in China. It is worth pointing out that, on March 12th, 1999, a boatload of illegal immigrants from China grounded and disembarked right on the northern beaches of Cairns at Holloways. They dispersed throughout the immediate area, taking two weeks to all be apprehended. One month later, our first two cases of squamous cell turned up within two days of each other - one from the suburb next to Holloways and the other from three suburbs away.
We contacted the immigration department to ask about what sort of medical procedures would have been invoked before the immigrants were returned to China and if any viral tests were done or tumours seen. However, they said that their medical examinations did not include any virus tests and no visible tumours were noted amongst the arrivals. Perhaps there is no connection at all but it remains a most interesting coincidence.
The table below lists the cases we have received of neoplasias (tumours). The species involved in ALL cases is Litoria infrafrenata except for record number 334 from Bayview Heights which was Litoria leseueri and case number 2365 - a new, unknown tumour type which has only appeared only in Litoria caerulea so far. (If you are referring to our information in your own reports or work, please provide a credit for our information and a copy of the resulting publication to us.) There are more potential tumour cases that have come in but without a biopsy, we didn't want to list them. Some of the vets in Cairns have also received neoplasia cases but we do not have records of what they have received.
A point about the identification methods we use: although our academic readers would be more confident if we always sent growths for an official biopsy result, each of these biopsies costs us $250+. Considering how distinctive some of these tumour types are and how many of them are arriving, we can't afford to pay $250 to verify something that looks to be certain. We use biopsies for the first couple cases or when a tumour is different. Additionally, to be fair, we can also point out that in many cases when we did send our cancer specimens to bonfide, accredited labs, the vast majority of our specimens either mysteriously "vanished" after arriving at those labs, or work was allegedly done but we were not provided with any results. That speaks volumes to us about the official lack of interest in these cases! We are far more selective now about who will be allowed to test our specimens.
|Record#||Arrived||Suburb||Tumour Type||ID Method|
|31||April 1999||Parramatta Park||naso. squamous cell||biopsy|
|32||April 1999||Machans Beach||naso. squamous cell||visual|
|137||May 2000||Machans Beach||internal squamous cell||post mortem|
|277||January 2001||Trinity Beach||naso. squamous cell and pre-cancerous cells on dorsum||biopsies|
|334||March 2001||Bayview Heights||unknown, contained melanin||biopsy|
|359||April 2001||Trinity Park||epidermal papillomas||visual from later biopsy, another frog|
|402||June 2001||Yorkeys Knob||unidentified growths||biopsy couldn't ID|
|404||July 2001||Holloways Beach||naso. squamous cell||visual|
|405||July 2001||Port Douglas||epidermal papillomas||biopsy|
|lost||2001||Edge Hill||epidermal papillomas||visual|
|lost||February 2002||Trinity Beach||epidermal papillomas||visual|
|937||January 2003||Gordonvale||naso. squamous cell||biopsy|
|1050||April 2003||Caravonica||possible adenocarcinoma||based on biopsy of later case|
|1063||May 2003||Kewerra Beach||epidermal papillomas||visual|
|1081||June 2003||Trinity Beach||sebaceous adenocarcinoma and epidermal papillomas||biopsy and visual|
|1086||June 2003||Whitfield||epidermal papillomas||visual|
|1122||August 2003||North Cairns||epidermal papillomas||visual|
|1166||October 2003||Kewerra Beach||extensive epid. papillomas||visual|
|1255||March 2004||Whitfield||pre-cancerous cells||visual|
|1288||May 2004||Machans Beach||naso. squamous cell||visual|
|1290||May 2004||Trinity Beach||epidermal papillomas||visual|
|1295||May 2004||Clifton Beach||epidermal papillomas||visual|
|1625||April 2006||Mooroobool||epidermal papillomas||visual|
|1713||October 2006||Machans Beach||osteosarcoma (chondrosarcoma)||verified by JCU|
|2069||June 2008||Trinity Beach||naso. squamous cell||visual, to Biosecurity Q.|
|2115||Oct 2008||Mundoo||epidermal papillomas||visual, to UQ|
|2149||Jan 2009||Manunda||naso. squamous cell||visual, to UQ|
|2235||Dec 2009||Machans Beach||naso. squamous cell||visual, to JCU|
|2260||Feb 2010||Clifton Beach||naso. squamous cell||visual, to UQ|
|2365||Feb 2011||Townsville||unknown tumour|
|2369||Mar 2011||Parramatta Pk||epidermal papillomas||visual, to DPI lab|
|2386||April 2011||Innisfail||unknown tumour (same as TNS case)|
|2551||Jan 2013||White Rock||naso. squamous cell||visual|
|2610||Jan 2014||Koah||epidermal papillomas||visual|
|3001||Dec 2018||White Rock||epidermal papilloma + mouth tumour||visual|
|3002||Dec 2018||Bingil Bay||early papilloma||visual|
|3003||Dec 2018||Bingil Bay||early papilloma||visual|
|3067||Oct 2019||Machans Beach||early squamous cell||visual|
|3084||Nov 2019||Aloomba||squamous cell||visual|
|3085||Dec 2019||East Feluga||epidermal papilloma||visual|
|3156||June 2020||Blackrock||spindle cell soft tissue sarcoma * note this case looks like an early version of case #402 which the lab used said they couldn't ID||lab verified, QML Vetnostics|
|3246||Jan 2021||Clifton Beach||neoplastic glaucoma||vet ID, Marlin Coast Vets|
|3255||March 2021||Mission Beach||epidermal papilloma||
|3303||July 2021||Holloways Bch||squamous cell carcinoma||visual|
|3327||Oct 2021||Moresby||papilloma||visual, labs pending|
|3379||March 2022||Cairns North||adenocarcinoma, squamous cell||Vetnostics|
|3444||Nov 2022||Carmoo||papilloma||visual, labs pending|
|3460||Dec 2022||Edge Hill||new tumour type||labs pending|
|3474||Jan 2023||Cooktown||papilloma, squamous||labs pending|
The gap in the cases between 2014 and 2018 is interesting but might simply reflect that frog numbers have dropped significantly since the malformations problem started in Jan 2003.
We would like to know urgently of any frogs you find with lumps on the face or body no matter where in the country you are so that we can verify if it is a neoplasia or might be another problem which can be treated. Always use gloves (or a plastic bag over your hand if nothing else is available) to handle a sick or injured frog and carry a couple clean, plastic containers with secure lids (air holes too please!) in your car, ready for anything you might find.