[Prognosis of canine oral (gingival) squamous cell carcinoma after surgical therapy. A retrospective analysis in 40 patients]

OBJECTIVE

Retrospective analysis of dogs with gingival squamous cell carcinoma (SCC) surgically treated using jaw resection. Material and me- thods: A total of 40 dogs were enrolled in the study. Dogs with incomplete tumour resection or metastases were subjected to adjuvant chemotherapy using carboplatin. Breed, age, tumour localisation, postsurgical complications, survival times and prognostic factors were evaluated.

RESULTS

There were no breed predispositions. The median age was 9.5 years (mean 8.6 years; range 0.5-15.5 years). At the time of presentation, two dogs (5%) had lymph node metastases (N1). The median survival time (ST) of all the patients was 44.8 months. In 15 patients, the tumour was located in the maxilla, whereas 25 dogs had a mandibular tumour location. The median ST in dogs with maxillary tumours was 39 months (95% confidence interval [CI] 24 months), while patients with maxillary tumours survived a median of 43 months (95% CI 33-70 months). There was no significant difference in the ST in patients with maxillary versus man- dibular tumours (p = 0.985). On multivariate analysis, only the tumour stage was found to be significantly associated with survival (p = 0.0047). Patients with stage N0 survived a median of 44 months (95% CI 36-80 months). The two dogs with lymph node metastasis (N1) sur- vived 18 and 70 months following jaw resection and carboplatin chemotherapy, respectively. According to the histological findings, tumour resection was incomplete in five patients. These dogs received adjuvant carboplatin chemotherapy, resulting in an ST of between 6 and 146 months.

CONCLUSION AND CLINICAL RELEVANCE

Prognosis depends on the tumour stage, while for complete local excision of the affected jaw segment a good prognosis can be given and the majority of the patients can be cured. The supposedly more malignant behaviour of gingival SCCs located in the caudal aspects of the oral cavity could not be confirmed. Patients with metastasis of the local lymph nodes can achieve acceptable survival times. Jaw resections have low complication rates and a good functional outcome.

Mode of action of Chrysosporium lucknowense C1 α-l-arabinohydrolases

The mode of action of four Chrysosporium lucknowense C1 α-L-arabinohydrolases was determined to enable controlled and effective degradation of arabinan. The active site of endoarabinanase Abn1 has at least six subsites, of which the subsites -1 to +2 have to be occupied for hydrolysis. Abn1 was able to hydrolyze a branched arabinohexaose with a double substituted arabinose at subsite -2. The exo acting enzymes Abn2, Abn4 and Abf3 release arabinobiose (Abn2) and arabinose (Abn4 and Abf3) from the non-reducing end of reduced arabinose oligomers. Abn2 binds the two arabinose units only at the subsites -1 and -2. Abf3 prefers small oligomers over large oligomers. It is able to hydrolyze all linkages present in beet arabinan, including the linkages of double substituted residues. Abn4 is more active towards polymeric substrate and releases arabinose monomers from single substituted arabinose residues. Depending on the combination of the enzymes, the C1 arabinohydrolases can be used to effectively release branched arabinose oligomers and/or arabinose monomers.

Chrysosporium lucknowense arabinohydrolases effectively degrade sugar beet arabinan

The filamentous fungus Chrysosporium lucknowense (C1) is a rich source of cell wall degrading enzymes. In the present paper four arabinose releasing enzymes from C1 were characterized, among them one endoarabinanase, two arabinofuranosidases and one exoarabinanase. Combinations of these enzymes released up to 80% of the arabinose present in sugar beet arabinan to fermentable monosugars. Besides the main product arabinobiose, unknown arabinose oligomers are produced from highly branched arabinan when endoarabinanase was combined with exoarabinanase and/or arabinofuranosidase. All described arabinose releasing enzymes are temperature stable up to 50 degrees C and have a broad pH stability. This makes C1 arabinohydrolases suitable for many biotechnical applications, like co-fermentation bioethanol production.

[Tonsillar squamous cell carcinoma in the dog. A retrospective study of 33 cases]

OBJECTIVE

Retrospective evaluation of clinical findings in 33 dogs with tonsillar squamous cell carcinomas.

MATERIAL AND METHODS

At the owners' request 9 patients were euthanized after diagnosis. 24 treated patients were grouped into six categories depending on the type of therapy: 1. tonsillectomy and NSAID (Piroxicam or Metacam) (n=10); 2. tonsillectomy, NSAID, and palliative radiation (24-30Gy in 3-5 fractions) (n=4); 3. tonsillectomy, NSAID, palliative radiation, and chemotherapy (5´ Carboplatin 280-300mg/m2 BSA) (n=3); 4. NSAID, palliative radiation, and chemotherapy (n=1); 5. NSAID alone (n=5), 6. tonsillectomy alone (n=1).

RESULTS

There were no breed predispositions but medium sized (10-20kg; 43%) and large dogs (>20kg; 20%), and males (n=22; 71%) were overrepresented. The average age was 10.7years (range, 6.5-14.5years). At the first presentation, 22 of the 33 dogs (67%) had lymph node metastasis. None of the dogs had lung metastasis at the time of diagnosis, as determined by three view chest X-rays. The best survival times (ST) were achieved in groups 2 and 3 with three of seven patients living longer than 1year. Patients without lymph node metastasis had a trend for longer survival times, independent of the type of therapy. Treated patients with lymph node metastasis (n=17) had a mean and median ST of 9.5 and 4months, respectively. Only two dogs survived longer than 1year. Dogs without lymph node metastasis had a mean and median ST of 17.7 and 12 months, respectively; the ST for four of the eight dogs exceeded 1year, two survived longer than 2years.

CONCLUSION

It could be confirmed that tonsillar squamous cell carcinomas are aggressive tumours with a high rate of cervical lymph node metastasis. In most cases with metastasis the survival times were relatively short, irrespective of treatment. In early stages of the disease however, good survival times could be achieved using surgical debulking followed by multimodality treatment.

CLINICAL RELEVANCE

In squamous cell carcinoma of the tonsils thorough staging is mandatory due to the high metastatic potential of the tumour. Verification of metastasis carries a poor prognosis. Further studies are required to find the best treatment (combination) for these patients.