Novel genomic prognostic biomarkers for dogs with cancer.

BACKGROUND: Growing evidence from dogs and humans supports the abundance of mutation-based biomarkers in tumors of dogs. Increasing the use of clinical genomic diagnostic testing now provides another powerful data source for biomarker discovery. HYPOTHESIS: Analyzed clinical outcomes in dogs with cancer profiled using SearchLight DNA, a cancer gene panel for dogs, to identify mutations with prognostic value. ANIMALS: A total of 127 cases of cancer in dogs were analyzed using SearchLight DNA and for which clinical outcome information was available. METHODS: Clinical data points were collected by medical record review. Variables including mutated genes, mutations, signalment, and treatment were fitted using Cox proportional hazard models to identify factors associated with progression-free survival (PFS). The log-rank test was used to compare PFS between patients receiving and not receiving targeted treatment before first progression. RESULTS: Combined genomic and outcomes analysis identified 336 unique mutations in 89 genes across 26 cancer types. Mutations in 6 genes (CCND1, CCND3, SMARCB1, FANCG, CDKN2A/B, and MSH6) were significantly associated with shorter PFS. Dogs that received targeted treatment before first progression (n = 45) experienced significantly longer PFS compared with those that did not (n = 82, P = .01). This significance held true for 29 dogs that received genomically informed targeted treatment compared with those that did not (P = .05). CONCLUSION AND CLINICAL IMPORTANCE: We identified novel mutations with prognostic value and demonstrate the benefit of targeted treatment across multiple cancer types. These results provide clinical evidence of the potential for genomics and precision medicine in dogs with cancer.

Outcome and prognosis for canine appendicular osteosarcoma treated with stereotactic body radiation therapy in 123 dogs.

Canine appendicular osteosarcoma is commonly treated with limb amputation; however, limb-sparing options are frequently desired or necessary for a subset of patients. We evaluated 123 patients and 130 sites treated with stereotactic body radiation therapy (SBRT). Eighty-two out of 98 dogs (84%) had maximum lameness improvement at a median of 3 weeks for a median of 6 months duration. Histopathologic evaluation of available samples from amputation or necropsy revealed >80% tumor necrosis in 50% of limbs consistent with local disease control. Of evaluable patients, 41% fractured and 21% pursued an amputation after treatment. Fine needle aspirate (n = 52) and needle core biopsy (n = 28) did not result in increased fracture risk compared to those without tumor sampling (n = 50). Median survival time (MST) was 233 days and time to first event was 143 days. Gross tumor volume and planned target volume were significantly inversely associated with survival and tumor location was significantly associated with survival. Dogs with salvage amputation had a significantly longer MST compared to those without (346 vs 202 days; P = .04). The presence of metastatic disease at the time of treatment in 15 dogs did not significantly impact survival time (200 vs 237 days without metastasis; P = .58). Skin side effects correlated significantly with dose with 33% of patients with acute grade 3 effects developing consequential late grade 3 effects. While SBRT improves lameness in most patients, further investigation is needed to identify candidates with minimal early fracture risk prior to initiating therapy.

Use of PET/CT and Stereotactic Radiation Therapy for the Diagnosis and Treatment of Osteosarcoma Metastases.

This case report describes the use of two new concepts in the diagnosis and treatment of metastatic osteosarcoma (OSA) in one dog. The dog was initially presented for positron emission tomography and computed tomography (PET/CT) as full-body staging following amputation and adjuvant chemotherapy for treatment of OSA of the proximal tibia. The initial PET/CT did not show evidence of metastatic disease. Six mo after OSA, diagnosis pulmonary metastatic nodules were identified and oral toceranib phosphate was initiated. Twelve mo postdiagnosis the dog developed neck pain and non-ambulatory tetraparesis and was diagnosed with a C7 vertebral metastatic lesion based on magnetic resonance imaging. A second PET/CT was performed to screen for further metastatic lesions, and a nodule within the right ischium was identified. The C7 and ischial lesions were treated with stereotactic radiation therapy (SRT). Sixteen mo postdiagnosis, a third PET/CT was performed due to increasing size of the pulmonary nodules and a right-sided liver metastasis was detected. The liver mass was treated with SRT. The PET/CT scans facilitated identification of gross metastatic lesions that were subsequently treated with SRT, which resulted in clinical improvement of the dog's neurological signs.

Combination Therapy with Zoledronic Acid and Parathyroid Hormone Improves Bone Architecture and Strength following a Clinically-Relevant Dose of Stereotactic Radiation Therapy for the Local Treatment of Canine Osteosarcoma in Athymic Rats.

Clinical studies using definitive-intent stereotactic radiation therapy (SRT) for the local treatment of canine osteosarcoma (OSA) have shown canine patients achieving similar median survival times as the current standard of care (amputation and adjuvant chemotherapy). Despite this, there remains an unacceptable high risk of pathologic fracture following radiation treatment. Zoledronic acid (ZA) and parathyroid hormone (PTH) are therapeutic candidates for decreasing this fracture risk post-irradiation. Due to differing mechanisms, we hypothesized that the combined treatment with ZA and PTH would significantly improve bone healing more than ZA or PTH treatment alone. Using an orthotopic model of canine osteosarcoma in athymic rats, we evaluated bone healing following clinically-relevant doses of radiation therapy (12 Gy x 3 fractions, 36 Gy total). Groups included 36 Gy SRT only, 36 Gy SRT plus ZA, 36 Gy SRT plus ZA and PTH, 36 Gy SRT plus PTH, and 36 Gy SRT plus localized PTH treatment. Our study showed significant increases in bone volume and increased polar moments of inertia (in the distal femoral metaphysis) 8 weeks after radiation in the combined (ZA/PTH) treatment group as compared to radiation treatment alone. Histomorphometric analysis revealed evidence of active mineralization at the study endpoint as well as successful tumor-cell kill across all treatment groups. This work provides further evidence for the expanding potential indications for ZA and PTH therapy, including post-irradiated bone disease due to osteosarcoma.

Advances in veterinary radiation therapy: targeting tumors and improving patient comfort.

Newer technology, such as intensity-modulated radiation therapy, can dramatically decrease acute radiation side effects, making patients more comfortable during and after treatment. Stereotactic radiation therapy for definitive treatment can be delivered in 1 to 5 fractions, with minimal radiation-associated effects. Image-guided radiation therapy can be used to direct treatment in locations previously not amenable to radiation therapy. Traditional fractionated radiation therapy remains the most commonly available type in veterinary medicine and is the standard of care for many tumors. This article discusses the role of advancements in the treatment of veterinary cancer patients and reviews more traditional radiation treatment.

Stereotactic body radiation therapy for treatment of injection-site sarcomas in cats: 11 cases (2008-2012).

OBJECTIVE: To evaluate outcomes of stereotactic body radiation therapy (SBRT) in cats with injection-site sarcomas (ISS) via assessment of local responses and recurrences, survival times, and complications. DESIGN: Retrospective case series. ANIMALS: 11 cats with ISS. PROCEDURES: Medical records of cats that were treated with SBRT for ISS between June 2008 and July 2012 were reviewed; information on patient demographics (age, sex, and breed), oncological histories (including prior treatment and histologic grade), details of SBRT plans (tumor volume, treatment field sizes, and prescription), response to treatment (including toxicoses), progression-free intervals, and survival times were extracted. RESULTS: Acute radiation-associated toxicoses were infrequent and limited to mild, self-limiting dermatitis and colitis in 2 and 1 of the 11 cats, respectively. No late radiation-associated toxicoses were observed. The objective response rate was 8 of 11 cats; these patients either had a partial or complete response as determined on the basis of CT or physical examination findings. The median progression-free interval was 242 days, and the median overall survival time was 301 days; median follow-up time of censored subjects was 173 days. CONCLUSIONS AND CLINICAL RELEVANCE: SBRT was completed in 3 to 5 days and was well tolerated when used to treat cats with ISS. Measurable tumor responses were achieved in most cats in this study. Stereotactic body radiation therapy provided a means for palliation of ISS; further investigation is required to determine whether SBRT is a valid treatment option for downstaging disease prior to definitive surgery.

Orthotopic model of canine osteosarcoma in athymic rats for evaluation of stereotactic radiotherapy.

OBJECTIVE: To develop an orthotopic model of canine osteosarcoma in athymic rats as a model for evaluating the effects of stereotactic radiotherapy (SRT) on osteosarcoma cells. ANIMALS: 26 athymic nude rats. PROCEDURES: 3 experiments were performed. In the first 2 experiments, rats were injected with 1 × 10(6) Abrams canine osteosarcoma cells into the proximal aspect of the tibia (n = 12) or distal aspect of the femur (6). Tumor engraftment and progression were monitored weekly via radiography, luciferase imaging, and measurement of urine pyridinoline concentration for 5 weeks and histologic evaluation after euthanasia. In the third experiment, 8 rats underwent canine osteosarcoma cell injection into the distal aspect of the femur and SRT was administered to the affected area in three 12-Gy fractions delivered on consecutive days (total radiation dose, 36 Gy). Percentage tumor necrosis and urinary pyridinoline concentrations were used to assess local tumor control. The short-term effect of SRT on skin was also evaluated. RESULTS: Tumors developed in 10 of 12 tibial sites and all 14 femoral sites. Administration of SRT to rats with femoral osteosarcoma was feasible and successful. Mean tumor necrosis of 95% was achieved histologically, and minimal adverse skin effects were observed. CONCLUSIONS AND CLINICAL RELEVANCE: The orthotopic model of canine osteosarcoma in rats developed in this study was suitable for evaluating the effects of local tumor control and can be used in future studies to evaluate optimization of SRT duration, dose, and fractionation schemes. The model could also allow evaluation of other treatments in combination with SRT, such as chemotherapy or bisphosphonate, radioprotectant, or parathyroid hormone treatment.

Evaluation of canine prostate intrafractional motion using serial cone beam computed tomography imaging.

This study used kilovoltage (kV) cone beam computed tomography (CBCT) imaging to characterize canine intrafractional prostate motion during hypofractionated stereotactic radiotherapy treatment. Serial CBCT images taken just prior to initiating treatment, and at several times during the treatment session, were acquired throughout the course of treatment for canine patients. All patients were immobilized in dorsal recumbency while using an air-inflated rectal balloon. For each treatment session, rigid registration of intrafraction CBCT images with the interfraction CBCT used for setup verification was performed. Contours of the prostate and urethra were drawn on each CBCT image set and the center of mass for each structure was evaluated as a function of time. A total of seven canine patients was included in the study, resulting in 41 CBCT images collected during a total of 12 treatment sessions. Over 70% of our data were collected for CBCTs taken between 20 and 51 min after final patient setup was complete. The mean intrafraction movement in a single direction for the prostate and urethra was ≤0.14 mm and ≤0.22 mm, respectively. The maximum intrafraction movement for the prostate and urethra was ≤ 1.60 mm and ≤ 2.00 mm, respectively. The maximum variability in intrafraction movement for the prostate and urethra, as defined by two standard deviations, was ≤1.40 mm and ≤1.50 mm, respectively. Minimal intrafraction variability using appropriate patient positioning and rectal balloon, combined with kV CBCT image-guided radiation therapy tools to account for interfraction changes, permit accurate and precise targeting of structures of interest.

Repeatability of a planning target volume expansion protocol for radiation therapy of regional lymph nodes in canine and feline patients with head tumors.

For canine and feline patients with head tumors, simultaneous irradiation of the primary tumor and mandibular and retropharyngeal lymph nodes (LNs) is often indicated. The purpose of this study was to assess the repeatability of a planning target volume (PTV) expansion protocol for these LNs. Two CT image sets from 44 dogs and 37 cats that underwent radiation therapy for head tumors were compared to determine LN repositioning accuracy and precision; planning-CT (for radiation therapy planning) and cone-beam CT (at the time of actual treatment sessions). Eleven percent of dogs and 65% of cats received treatment to their LNs. In dogs, the mandibular LNs were positioned more caudally (P = 0.0002) and the right mandibular and right retropharyngeal LNs were positioned more to the left side of the patient (P = 0.00015 and P = 0.003, respectively). In cats, left mandibular LN was positioned higher (toward roof) than the planning-CT (P = 0.028). In conclusion, when the patient immobilization devices and bony anatomy matching are used to align the primary head target and these LNs are treated simultaneously, an asymmetrical PTV expansion that ranges 4-9 mm (dogs) and 2-4 mm (cats), depending on the directions of couch movement, should be used to include the LNs within the PTV at least 95% of the time.

Quantitation of and superficial surgical landmarks for the anterior interosseous nerve.

OBJECT: There are scant data regarding the anterior interosseous nerve (AIN) in the neurosurgical literature. In the current study the authors attempt to provide easily identifiable superficial osseous landmarks for the identification of the AIN. METHODS: The AIN in 20 upper extremities obtained in adult cadaveric specimens was dissected and quantified. Measurements were obtained between the nerve and surrounding superficial osseous landmarks. The AIN originated from the median nerve at mean distances of 5.4 cm distal to the medial epicondyle of the humerus and 21 cm proximal to the ulnar styloid process. The distance from the origin of the AIN to its branch leading to the flexor pollicis longus muscle and to the point it travels deep to the pronator quadratus (PQ) muscle measured a mean 4 and 14.4 cm, respectively. The mean distance from the AIN branch leading to the flexor pollicis longus muscle to the proximal PQ muscle was 12.1 cm, and the mean distance between this branch and the ulnar styloid process was 7.2 cm. The mean diameter of the AIN was 1.6 mm at the midforearm. CONCLUSIONS: Additional landmarks for identification of the AIN can aid the neurosurgeon in more precisely isolating this nerve and avoiding complications. Furthermore, after quantitation of this nerve, the AIN branches can be easily used for neurotization of the median and ulnar nerves, and with the aid of a transinterosseous membrane tunneling technique, passed to the posterior interosseous nerve.

Quantitation of and landmarks for the muscular branches of the ulnar nerve to the forearm for application in peripheral nerve neurotization procedures.

OBJECT: In neurotization procedures, donor nerves--either whole or in part-with relatively pure motor function can be carefully chosen to provide the optimal nearby motor input with as little donor site morbidity as possible. In this context, the ulnar nerve branches to the forearm muscles are relatively dispensable; however, quantitation of and landmarks for these branches are lacking in the literature. METHODS: The ulnar branches to the flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP) muscles in 20 upper extremities obtained in adult cadaveric specimens were dissected and quantified. In the forearm, a mean of four nerve branches led to the FCU and FDP muscles. A mean of 3.4 branches led to the FCU muscle; of these, one to three were medial branches and zero to two were lateral. Medial branches to the FCU muscle originated a mean of 2.7 cm inferior to the medial epicondyle. Lateral branches to the FCU muscle originated at a mean of 3.3 cm inferior to the medial epicondyle. The mean length of the medial branches was 3.2 cm, whereas the mean length of the lateral branches was 3.3 cm. All nerves had a single trunk for the FDP muscle, and in all specimens this branch was located deep to the main ulnar nerve trunk, originating from the ulnar nerve a mean of 2.7 cm inferior to the medial epicondyle. These branches had a mean length of 5.6 cm. The mean diameter of all medial and lateral branches to the FCU muscle was 1 mm, and the mean diameter of the branch to the FDP muscle was 2.1 mm. All branches to both the FCU and FDP muscles arose from the ulnar nerve, over its first approximately 5 cm from the level of the medial epicondyle. Additionally, all branches could be easily lengthened by gentle proximal dissection from the main ulnar nerve. CONCLUSIONS: Ulnar branches to the forearm can be easily localized and used for neurotization procedures. The branch to the FDP muscle had the greatest diameter and longest length, easily reaching the median nerve and posterior interosseous nerve via a transinterosseous membrane tunneling procedure. Furthermore, this branch could be teased away from the main ulnar nerve trunk and made to reach the distal branches of the musculocutaneous nerve in the arm.

Surgical anatomy of the cervical and infraclavicular parts of the long thoracic nerve.

OBJECT: There is insufficient information in the neurosurgical literature regarding the long thoracic nerve (LTN). Many neurosurgical procedures necessitate a thorough understanding of this nerve's anatomy, for example, brachial plexus exploration/repair, passes for ventriculoperitoneal shunt placement, pleural placement of a ventriculopleural shunt, and scalenotomy. In the present study the authors seek to elucidate further the surgical anatomy of this structure. METHODS: Eighteen cadaveric sides were dissected of the LTN, anatomical relationships were observed, and measurements were obtained between it and surrounding osseous landmarks. The LTN had a mean length of 27 +/- 4.5 cm (mean +/- standard deviation) and a mean diameter of 3 +/- 2.5 mm. The distance from the angle of the mandible to the most proximal portion of the LTN was a mean of 6 +/- 1.1 cm. The distance from this proximal portion of the LTN to the carotid tubercle was a mean of 3.3 +/- 2 cm. The LTN was located a mean 2.8 cm posterior to the clavicle. In 61% of all sides the C-7 component of the LTN joined the C-5 and C-6 components of the LTN at the level of the second rib posterior to the axillary artery. In one right-sided specimen the C-5 component directly innervated the upper two digitations of the serratus anterior muscle rather than joining the C-6 and C-7 parts of this nerve. The LTN traveled posterior to the axillary vessels and trunks of the brachial plexus in all specimens. It lay between the middle and posterior scalene muscles in 56% of sides. In 11% of sides the C-5 and C-6 components of the LTN traveled through the middle scalene muscle and then combined with the C-7 contribution. In two sides, all contributions to the LTN were situated between the middle scalene muscle and brachial plexus and thus did not travel through any muscle. The C-7 contribution to the LTN was always located anterior to the middle scalene muscle. In all specimens the LTN was found within the axillary sheath superior to the clavicle. Distally, the LTN lay a mean of 15 +/- 3.4 cm lateral to the jugular notch and a mean of 22 +/- 4.2 cm lateral to the xiphoid process of the sternum. CONCLUSIONS: The neurosurgeon should have knowledge of the topography of the LTN. The results of the present study will allow the surgeon to better localize this structure superior and inferior to the clavicle and decrease morbidity following invasive procedures.

Landmarks for the greater petrosal nerve.

The anatomy of the greater petrosal nerve while within the middle cranial fossa is lacking in the English literature and must be well understood by the surgeon who operates in this area. Twenty-two sides from six female and five male cadavers were examined. Measurements were made between the greater petrosal nerve as it coursed through the middle cranial fossa and surrounding structures such as the arcuate eminence and lateral wall of the middle cranial fossa. Mean distances from the arcuate eminence to the hiatus of the greater petrosal nerve into the middle cranial fossa measured 17.5 mm (SD = 2.2). The length of this nerve within the middle fossa was approximately 10 mm (SD = 2). From the lateral wall of the middle fossa to a midpoint of the greater petrosal nerve mean distances measured 39 mm (SD = 2.4). The mean distance from the foramen spinosum to the exit of this nerve inferior to the trigeminal ganglion measured 7 mm (SD = 1.8). These measurements will hopefully aid the surgeon who wishes to expose or avoid the greater petrosal nerve within the middle cranial fossa.

Degree of tectal beaking correlates to the presence of nystagmus in children with Chiari II malformation.

INTRODUCTION: Tectal beaking is a common finding in children born with a myelomeningocele. Quantitation of the presence or absence of this finding correlated with normal or abnormal eye movements is lacking in the medical literature. MATERIALS AND METHODS: We prospectively evaluated 50 children in our multidisciplinary spina bifida clinic. Each child was observed for the presence or absence of nystagmus at rest or with extraocular movement. Grades of nystagmus and severity of tectal beaking (Types I-III) on MRI were then correlated. RESULTS: Overwhelmingly, children with greater dysmorphology of the mesencephalic tectum were most likely to have nystagmus. Higher grades of nystagmus were associated with Type III tectal beaking. CONCLUSIONS: We have demonstrated that there is a correlation between the presence and severity of nystagmus and the severity of tectal beaking and have quantified this association in patients with the Chiari II malformation. This information may act as a guide in predicting which children with the Chiari II malformation will have significant nystagmus. These data may aid the clinician in the interpretation of oculomotor abnormalities in this cohort of patients.