Page 554 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

532 PART IV Specific Malignancies in the Small Animal Patient

Higher histologic grade and mitotic index may be predictive for Disease-Free Interval
a poorer prognosis; however, the prognostic value of histologic 1 1
grade for predicting biologic behavior remains controversial as
VetBooks.ir study results are contradictory. 104,105 0.9 0.9
0.8
0.8
The biologic behavior for less common appendicular (ulna)
and nonappendicular sites of OSA appears to be similar (aggres- 0.7 0.7
sive), with the exception of the mandible and possibly other cal- 0.6 0.6
varial sites. 120,122,123,166–168 OSA of the head (mandible, maxilla,
and skull) is locally aggressive but has a lower metastatic rate than Proportion surviving 0.5 0.5
appendicular OSA. 124 In a study of 183 dogs, local recurrence 0.4 0.4
or progression occurred in 51.3% of dogs, and 38.5% of dogs 0.3 0.3
developed distant metastases; the overall MST was 239 days. 124 0.2 0.2
Dogs with OSA of the mandible treated with mandibulectomy
alone had a 1-year survival rate of 71% in one study, 122 suggest- 0.1 0.1
ing a less aggressive biologic behavior. A second study of 50 dogs 0 0
with mandibular OSA also confirmed improved STs relative to 0 200 400 600 800 1000
appendicular OSA; however, the majority of dogs (58%) still Time (days)
developed metastatic disease, and the addition of adjuvant chemo-
therapy to mandibulectomy resulted in a significantly improved BALP 23 U/L
BALP 23 U/L
ST. 125 In contrast, maxillary OSA has a MST of 5 months after A
maxillectomy. 167,168 The MST for dogs with rib OSA lesions is 3
months after chest wall resection alone and 8 months after treat-
ment with chest wall resection and adjuvant chemotherapy. 169–172 Survival
Scapular OSA has a guarded prognosis when treated with subtotal 1 1
scapulectomy surgery and chemotherapy; 165,173,174 The DFI and
MST in dogs diagnosed with scapular OSA were 210 days and 0.8 0.8
246 days, respectively. 121 Limb function after subtotal scapulec-
tomy is good to excellent. 121 Survival of dogs with OSA distal to 0.6 0.6
the antebrachiocarpal or tarsocrural joints was somewhat longer
(MST 466 days) than survival of dogs with OSA of more common Proportion surviving
appendicular sites; however, OSA in these sites is aggressive with a 0.4 0.4
24
high potential for metastasis. Vertebral OSA is uncommon, but
it is locally aggressive and local tumor recurrence or progressive 0.2 0.2
disease is common after conservative surgical approaches. 21,175 In
15 dogs treated with a combination of surgery, RT, and chemo- 0 0
therapy, the MST was 4 months. 175 For dogs with pelvic OSA 0 500 1000 1500
treated with hemipelvectomy, the local recurrence and metastatic Time (days)
rates were 21% and 46%, respectively, with a mean ST of 533 TALP 110 U/L
days and 1- and 2-year survival rates of 53% and 35%, respec- TALP 110 U/L
tively. 176 The biologic behavior of OSA in other nonappendicular B
bone sites has not been thoroughly evaluated.
Extraskeletal OSA is rare and most commonly affects visceral sites • Fig. 25.4 (A) Disease-free interval outcome of dogs treated for osteo-
sarcoma comparing preoperative bone alkaline phosphatase levels higher
(gastrointestinal [GI] tract, spleen, liver, kidney, urinary bladder), skin than and lower than 23 U/L. (B) Survival outcome of dogs treated for
or subcutaneous tissue, or mammary glands. Extraskeletal (soft tissue) osteosarcoma comparing preoperative serum alkaline phosphatase lev-
OSA sites also appear to have aggressive systemic behavior with a high els higher than and lower than 110 U/L. (Reprinted with permission from
metastatic rate. In one report, dogs with extraskeletal OSA treated with Ehrhart N, Dernell WS, Hoffmann WE, et al. J Am Vet Med Assoc. 1998;
surgery alone had a MST of only 1 month, and dogs treated with sur- 213:1002–1006. 178 )
gery and adjuvant chemotherapy had a MST of 5 months. In a larger
27
study, soft tissue and mammary OSAs were separated; the MST for soft tissue metastases (19 days). Dogs with LN metastasis have a
dogs with nonmammary gland soft tissue OSA was 1 month and 3 significantly shorter MST (59 days) than dogs without LN metas-
months for dogs with mammary gland OSA after surgical resection tasis (318 days). 113,114 In dogs with stage III disease treated with
28
alone. The major cause of death was local recurrence (92%) in dogs metastasectomy, the MST (232 days) was significantly longer than
with soft tissue OSA cases and pulmonary metastasis (62.5%) in dogs for dogs not treated with metastasectomy (49 days). 177
with mammary gland OSA.
Dogs presenting with stage III disease (measurable metasta- Serum Alkaline Phosphatase
sis) have a very poor prognosis; however, improved survival may Elevated alkaline phosphatase (ALP) has been clearly associated
be achievable when appropriate metastasectomy (tumor control with a poorer prognosis for dogs with appendicular and rib OSA
>300 days and <3 pulmonary nodules) is performed. 114,177 The in several individual studies 113,162,178–181 and two recent large meta-
MST for 90 dogs with stage III disease at presentation was 76 analyses. 159,164 A preoperative elevation of either total (serum)
days. Dogs with bone metastasis (132 days) had a longer ST (132 or bone isoenzyme of ALP (greater than 110 U/L or 23 U/L,
days) than dogs with lung metastasis (59 days) or lung and other respectively) is associated with a shorter DFI and ST (Fig. 25.4).