In 1991, the International Registry of Lung Metastases was established. Five thousand two hundred

six cases of pulmonary metastases were analyzed retrospectively with regard to prognostic variables.197

Multivariate analysis showed a better prognosis for patients with germ cell tumors, a disease-free

interval of 36 months or more, a single metastasis, and complete resection. A simple system of

classification into prognostic groups was designed (Table 79-11).

Several guidelines must be met before a patient is considered for resection of pulmonary metastases:

(a) control of the primary tumor, (b) absence of extrathoracic metastases, (c) a general medical

condition that permits thoracotomy or thoracoscopy, (d) pulmonary function that allows complete

resection of all metastases, and (e) lack of a more effective systemic treatment. Resection should be

undertaken only if complete resection is considered technically feasible.204

RESULTS

Table 79-11 Survival by Prognostic Group: The International Registry of Lung

Metastases

If the metastatic lesion is found at the same time as a recurrence at the primary site, the recurrent

primary tumor should be treated before the metastatic disease is resected to prevent further tumor

seeding. When the primary tumor and the metastasis are diagnosed simultaneously, lung resection may

precede operation for the primary disease if it is doubtful whether the pulmonary disease can be

completely resected, and immediate subsequent resection of the primary tumor is planned.

When a patient meets the criteria for resection of one or more pulmonary metastases, the natural

history of the tumor and whether effective systemic therapy is available must be considered. Experience

in breast cancer, testicular cancer, and osteogenic sarcoma illustrate this point.205 In contrast to

metastatic sarcoma, which is usually confined to the lungs, metastatic breast cancer to the lungs signals

the development of widely disseminated disease. Although effective systemic therapy is available,

patients with a solitary metastatic lesion, long disease-free interval following treatment for the primary

breast cancer and good performance status appear to have longer median and 5-year survival following

pulmonary resection.206,207

The advent of effective chemotherapy has altered the management of pulmonary metastases of germ

cell cancer and rendered an incurable disease curable. Platinum-based chemotherapy is now the primary

form of treatment.208 Resection is reserved for patients who have a complete serologic response

(normal levels of ß-human chorionic gonadotropin and α-fetoprotein) with residual pulmonary lesions,

evidence of persistent intrathoracic disease with elevated markers despite a full course of

chemotherapy, or lesions that do not respond or that progress with chemotherapy.209 Approximately

one-third of the resected pulmonary lesions contain viable tumor, one-third contain fibrosis or necrosis,

and one-third are teratomas. A teratoma is removed to prevent it from degenerating to a more

malignant form of germ cell tumor and to avoid the potential complications of local tumor growth.

Residual tumors are found mostly in patients with positive serology, and the prognosis is usually not as

good as when no residual disease is present.210 In addition, the presence of residual pulmonary disease,

as opposed to mediastinal disease, appears to portend a worse survival. Patients who are fit for

operation can derive significant long-term survival even though thoracic metastasectomy has a strictly

adjuvant role in the treatment of malignant germ cell tumors.211

The development of more effective chemotherapy regimens for sarcomas, especially osteogenic

sarcomas, has also altered the management of pulmonary metastases in this disease. Resection is part of

a multimodality treatment approach, but the manner in which chemotherapy and resection should be

combined is less clear than in germ cell cancer. The timing of an operation in relation to chemotherapy

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depends on the number, size, and location of pulmonary metastases at diagnosis and on whether the

patient has received any previous chemotherapy. Often, resection is performed between cycles of

chemotherapy, with the aim of controlling both gross and micrometastatic disease. This approach allows

the sensitivity of the patient’s tumor to chemotherapy to be assessed, and the advisability of continuing

the regimen postoperatively can be determined. The thoracic surgeon should collaborate with the

medical and radiation oncologists in planning a multidisciplinary treatment program for patients with

pulmonary metastases from sarcoma.

Preoperative Evaluation

The preoperative evaluation of the patient undergoing resection of pulmonary metastases is similar to

that of the patient undergoing removal of a primary lung cancer. Tests including pulmonary function,

arterial blood gases, and, if necessary, ventilation–perfusion lung scanning are performed to be sure that

the patient has sufficient reserve to tolerate complete resection of the metastases. The pulmonary

function of patients who received chemotherapy may be substantially reduced. This is particularly true

of patients treated with bleomycin and mitomycin, which can markedly diminish the diffusion capacity

and, occasionally and unpredictably, cause an acute respiratory distress type of syndrome

postoperatively. Maintaining patients on 35% or less inspired oxygen intraoperatively is thought to help

prevent this complication. Like patients with primary lung cancers, these patients should stop smoking.

Patients who smoke actively up to the time of operation are at risk for postoperative atelectasis or

pneumonia.

It is also important to assess the patient’s general medical condition and cardiovascular status. Older

patients may have underlying coronary artery disease that requires preoperative treatment and

additional perioperative monitoring. The cardiac function of patients who previously received

chemotherapy, especially doxorubicin, may be impaired. A preoperative radionuclide scan or

echocardiogram should be performed to determine the left ventricular ejection fraction and assess

whether intraoperative hemodynamic monitoring is necessary. Other drugs, such as cisplatin, can impair

renal or neurologic function and may influence perioperative management.

If a patient has recently undergone chemotherapy, the timing of surgery should be planned after

consultation with the medical oncologist, so that the operation is not performed when the patient is

neutropenic or thrombocytopenic. Resumption of chemotherapy postoperatively should also be a joint

decision between the surgeon and medical oncologist so that it does not compromise wound healing.

Surgical Technique

Two principles guide the approach to resecting pulmonary metastatic lesions; complete resection of

disease and maximal sparing of functioning lung tissue. Wedge resections should be performed

whenever possible. A lobectomy or even a pneumonectomy may be performed when wedge resection

will not provide a complete resection. This may be necessary for recurrences (completion

pneumonectomy), centrally located tumors, or multiple metastases.212,213

Unilateral disease is approached by a standard anterolateral or posterolateral thoracotomy incision.

Patients with bilateral pulmonary metastases should have a simultaneous resection of the bilateral

lesions if technically feasible. This can be accomplished by a median sternotomy or a clamshell incision

(bilateral anterior thoracotomy with or without transverse sternotomy). A clamshell incision provides

better exposure to the posterior aspects of the lungs, particularly the left lower lobe, which is difficult

to access by a median sternotomy.214 Bilateral pulmonary nodules may require sequential posterolateral

thoracotomies if they are centrally located and good exposure of the hilar vessels is needed.

The role of VATS in the management of patients with isolated suspected pulmonary metastasis is clear

when performed for diagnostic purposes. VATS wedge resection can be carried out with a high degree

of success and minimal morbidity.215 Although the use of thoracoscopy in the resection of pulmonary

metastases is increasing, its use remains controversial. In a series of 318 patients reported by Petersen

et al. undergoing resection of metastatic melanoma, 40 patients underwent thoracoscopic resection.216

According to the authors, thoracoscopy has been their preferred approach to metastasectomy in the past

few years utilizing chest CT for preoperative localization and ring clamp or digital palpation for

intraoperative confirmation.

Gossot et al. compared 31 patients undergoing thoracoscopic resection to 29 patients undergoing

thoracotomy for resection of metastatic sarcoma.217 They found no significant difference in 1-, 3-, or 5-

year survival. There was also no significant difference in disease-free survival. They recommend a

minimally invasive approach for patients with less than two pulmonary nodules that are both amenable

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to wedge resection with no mediastinal or chest wall invasion. Thoracoscopic resection may also be

beneficial in terms of causing fewer adhesions as Briccoli et al. have shown that 35% of patients

undergoing metastasectomy for sarcoma will require a repeat resection resulting in acceptable survival

rates as long as pulmonary function is maintained.218

Table 79-12 Histologic Subtypes from the International Registry of Lung

Metastases

Results

Resection remains the mainstay of treatment for pulmonary metastases from solid tumors that cannot be

treated effectively with chemotherapy, including melanoma, colon, renal cell, sarcoma, head and neck,

and endometrial cancers. The histologic subtypes of the pulmonary metastases in the International

Registry of Lung Metastases are listed in Table 79-12.197

Globally, the actuarial survival after complete metastasectomy is 36% at 5 years and 26% at 10 years

(median survival of 35 months).197 The experience at Memorial Sloan-Kettering Cancer Center in the

resection of pulmonary metastases from renal cell carcinoma, head and neck tumors, colorectal cancers,

testicular germ cell tumors, and soft-tissue sarcoma are summarized (Table 79-13). These results again

demonstrate that complete resection of metastatic disease is associated with prolonged survival in

carefully selected patients. Furthermore, patients who are persistently free of disease at the primary

tumor location but who have recurrent resectable metastatic disease of the lung also benefit from

repeated surgery.219 Mortality rates of pulmonary metastasectomy do not differ from those of thoracic

surgery performed for lung cancers, varying between 0.6% and 2%.190,209,220 The surgical removal of

pulmonary metastases is widely accepted, but its role has changed as more effective chemotherapy has

become available for some cancers. It is important that the surgeon understand the indications for

operation, the potential side effects of initial chemotherapy, and the ways in which resection should be

integrated into the overall treatment plan for these patients.

RESULTS

Table 79-13 Results of Pulmonary Resections for Metastases at Memorial SloanKettering Cancer Center

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