Page 533 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 24 Tumors of the Respiratory System 511

Treatment successfully in five dogs. 341 Cases that were deemed to be good
candidates for thoracoscopic removal in this study included dogs
VetBooks.ir Surgery with small masses located distant to the hilus. Caudal lung lobec-
tomy was easier than cranial lung lobectomy; however, both were
341
Conversion rates for thoracoscopic
Surgery is the treatment of choice for dogs and cats with primary
performed successfully.
pulmonary tumors. The surgical approach to a pulmonary tumor lung lobectomy are between 9% to 23% and conversion is most
is dependent on the clinician and tumor location, but certain commonly performed due to poor visualization. 341,344,345 One-
overarching criteria exist. For unilateral tumors, a lateral thora- lung ventilation should be considered in cases of thoracoscopic
cotomy is preferred, but a median sternotomy approach can also lung lobectomy to improve visualization. 341,342,346,347
be used. Thoracoscopic lung lobectomy is feasible if the mass is Biopsy of tracheobronchial LN is recommended in dogs and
peripherally located and in a suitable location; however, this sur- cats as a staging tool, as metastatic disease to the LN significantly
gery requires advanced training in minimally invasive procedures. affects prognosis. 284,287 The LNs are located dorsally along the
If nodules in multiple lobes are found bilaterally and the goal is trachea and bronchi, and hence exposure may be better via a lat-
to remove all gross disease, then a median sternotomy should be eral thoracotomy compared with a median sternotomy. Thoraco-
performed. scopic LN biopsy is performed regularly in human lung cancer
Both partial and complete lung lobectomies have been patients, 341,348 and this was recently described in dogs. 349 In this
described and the elected technique is based on the location of report, seven of eight purpose-bred research dogs successfully
the tumor. In general, a complete lung lobectomy should be per- underwent tracheobronchial LN extirpation. Complications were
formed; however, partial lung lobectomy may be an option for minor, although further study is needed to determine the use of
small tumors located in a peripheral position on the lung lobe this technique in clinical patients. 349
or for pulmonary metastatectomy. A cuff of normal tissue should
be removed with the tumor to increase the chance of obtaining a Chemotherapy
wide margin.
Partial and complete lung lobectomies are generally performed Cisplatin-based chemotherapy protocols are considered the stan-
with either a suturing method or the use of a surgical stapler. When dard of care for human lung cancer patients, either in the adjuvant
performing a partial lung lobectomy with the suture method, the or palliative setting. 350 Relatively little is known about the effi-
area to be removed is delineated by placing crushing forceps proxi- cacy of chemotherapy for pulmonary tumors in domestic animals;
mal to the lesion. 336 A continuous overlapping suture can then be however, chemotherapy has been largely unrewarding in the gross
placed proximal to the clamps. 336 The pulmonary artery and vein disease setting. Early clinical trials evaluating the safety and effi-
are individually ligated, and the bronchi are oversewn to prevent cacy of doxorubicin in cancer-bearing pet dogs included one dog
air leakage. 334 with papillary pulmonary adenocarcinoma, and this dog had pro-
Several studies have evaluated the use of stapling equipment for gressive disease. 351 No responses were seen in three dogs with lung
lung lobectomy. 282,337,338 In a study of 37 dogs and cats undergo- adenocarcinoma treated with mitoxantrone. 352 Minimal responses
ing resection of pulmonary lesions (67% were neoplastic) with were reported in two dogs treated with vindesine, whereas two
surgical staplers, complications were minimal and the technique dogs treated with the combination of vindesine and cisplatin both
was considered safe, fast, and efficient. 337 Use of surgical staplers experienced greater than 50% reduction in measurable disease. 282
is widely considered to be the technique of choice for partial and Treatment with vinorelbine resulted in partial responses in two of
complete lung lobectomy. seven dogs with measurable bronchoalveolar carcinoma. 353 Three
Two recent studies evaluated outcomes after pneumonectomy, additional dogs with microscopic disease were treated with adju-
which is defined as the removal of the entire left or right lung vant vinorelbine in the microscopic disease setting, and these dogs
fields. 339,340 In total, 33 dogs and 17 cats had a pneumonectomy had individual survival times (STs) of 113, 169, and greater than
performed and, of these, 18 dogs and 4 cats were diagnosed with 730 days. 353 Pharmacokinetic studies in humans have concluded
pulmonary neoplasia. 339,340 Perioperative mortality rates were that vinorelbine treatment results in 300-fold higher concentra-
low with 94% of dogs and 86% of cats surviving to discharge tion in the lung compared with plasma, which is 3.4- and 13.8-
in one study. 340 The partial pressure of oxygen was significantly fold higher than lung concentrations of vindesine and vincristine,
higher and alveolar-arterial gradient was significantly lower post- respectively. 354 Based on observed partial responses in dogs and
pneumonectomy compared with dogs treated with single lung pharmacokinetic data in people, treatment with vinorelbine or
lobectomy. 340 cisplatin appears to hold the most promise for dogs with primary
Thoracoscopy can be used to explore the thoracic cavity, lung carcinoma. CCNU (lomustine) is recommended for dogs
obtain biopsies (Fig. 24.15), 327,328 and perform thoracoscopic with localized pulmonary HS. 355
or thoracoscopic-assisted lung lobectomy. 341–345 In the largest Delivery of aerosolized chemotherapy or cytokines has been
study to date, 22 medium-to-large breed dogs underwent video- described and appears well tolerated in dogs with primary or met-
assisted thoracoscopic surgery (VATS) for lobectomy of primary astatic pulmonary neoplasia. Complete and partial responses have
lung tumors, and this group was compared with a cohort of dogs been described in dogs treated with inhalational therapy for meta-
treated with lung lobectomy via an open thoracotomy. 345 In this static tumors, whereas stable or progressive disease was reported in
study, an endoscopic stapler was used for lung lobectomy via either dogs with primary lung tumors. 356,357
a three- or four-port technique. 345 Short-term complications were Treatment with monoclonal antibodies or small-molecule tyro-
similar between the two approaches, and all VATS patients sur- sine kinase inhibitors (TKIs) directed against cell signaling path-
vived to discharge. Surgery time for VATS was significantly longer ways have been shown to be beneficial in distinct subpopulations
than open thoracotomy (120 vs. 95 minutes, respectively). 345 In a of human patients with nonsmall cell lung cancer (NSCLC). Such
second study of nine dogs with either primary or metastatic pul- targeted therapies have yet to be thoroughly examined in dogs
monary neoplasia, thoracoscopic lung lobectomy was performed with primary lung tumors. In a phase I study, monotherapy with