Laser Assisted Pulmonary Metastasectomy

WHAT IS LAPM?

Removal, also called resection or excision, of pulmonary metastasis is called pulmonary metastasectomy. It is not a new operation. Weinlechner in 1882 first performed pulmonary metastasectomy along with resection of primary chest wall sarcoma. The operation, as an independent entity, was first described by Divis in 1926. There are many ways to do this operation. When modern 1318nm diode lung laser is used for this operation, it is called Laser Assisted Pulmonary Metastasectomy (LAPM).

WHO SHOULD UNDERGO LAPM?

Any patient with metastasis in lungs must be evaluated for LAPM. If the primary disease is completely under control, if the cancer spread is strictly restricted to lungs, if the disease in lungs can be completely removed by surgery and if patient is physically fit to undergo the surgery, he or she qualifies for LAPM.

PRE-OPERATIVE STUDIES BEFORE LAPM

These studies are generally individualised. At first, control of primary cancer must be ascertained. Next, routine blood tests, chest X-ray, pulmonary function tests, EKG, blood gas analysis, tumour marker studies, stress testing, abdominal ultrasound, CT-scan, MRI, PET-CT, GI endoscopy etc. are usually considered.

Limitations of CT-scan in diagnosing lung metastasis must be clearly understood. Firstly, all nodules seen on CT-scan are not metastatic in nature. Many of them, especially in case of breast cancer, could either be non-cancerous or second primary lung cancer. It is for this reason, too, LAPM should be considered as a diagnostic aid paving way for correct treatment.

Secondly, a most sophisticated CT-scan also misses a metastatic nodule smaller than 3 to 4 mm in size. On the other hand, careful inspection of lung through open chest and exploration by surgeon’s experienced fingers can detect 25% more nodules , as small as 1 mm in diameter, which are missed by CT-scan. It is for this reason that any technique of pulmonary metastasectomy which does not permit digital exploration by surgeon is not a proper way of handling the disease. A clear example of this is Video Assisted Thoracic Surgery (VATS) for this operation. It can leave disease behind which LAPM can easily remove.

PRE-OPERATIVE PREPARATION BEFORE LAPM

Again these are individualised and mostly done on out-patient basis. All patients undergo thorough medical and anaesthetic evaluation. They work on incentive spirometry during every waking hour. Aggressive chest physiotherapy helps in early recovery. Bronchospasm, diabetes mellitus and hypertension must be controlled well. Smoking must be avoided at least a week prior to surgery. Inhalers, nebulisation and steam inhalation improve lung health. Patients receive mild sedation on previous night.

LAPM-THE OPERATION

Patient is put to sleep by general anaesthesia. Chest is entered through a small cut underneath the armpit. No muscle or rib is cut or removed. A spreader is inserted between the two ribs and ribs are spread apart. Surgeon carefully inspects and explores the entire lung with fingers. Thus he detects and notes the site and number of cancerous nodules.

One after the other, all nodules are removed along with a margin of 2-3 mm of healthy lung around them. Surgeon follows the contour of the nodule and goes all around in the healthy lung. One nodule usually takes 1-2 minutes. Though laser generates temperature of 700 degree Celsius, healthy lung is not damaged. Usually 7-8 nodules are removed from each lung but even 100 can be removed in the same fashion. Very tiny nodules can be vaporised instead removed.

Excised tumours can be subjected to pathological studies. Raw areas can be sutured back leaving lung nearly normal. Loss of lung tissue is hardly 10%. There is very little blood loss and hence, no blood transfusion is required. Total operating time varies between 1 and 2 hours. Complication rate is hardly 1 to 2 %. Mortality is rare.  

POST-OPERATIVE COURSE AFTER LAPM

Most of the patients either do not need any ICU care or need it only for 2 to 24 hours. Most of the pre-operative measures are continued post-operatively. Nasal oxygen cannula stays for 3 to 6 hours. Need for ventilator is very rare. Analgesics-epidural, IV and oral- are given liberally. IV fluids are needed for the first day. Oral liquids are started from the evening of the day of operation and normal diet is started from the next day. Removal of the chest tube and ambulation begin on 2nd or 3rd day. Most often, patient stays in hospital for 3 to 5 days depending on their tolerance to pain. Pre-discharge chest X-ray is taken.

SURVIVAL AFTER LAPM

There is 3 to 5 % 5-year survival after development of pulmonary metastasis. This is in sharp contrast to 5 and 10-year survival after LAPM nearing 35-40% and 26% respectively. For breast cancer, it is 50%, for renal cell and colon cancer, 40% and melanoma, 20%.  

FOLLOW UP AFTER LAPM

Chest x-ray is needed once every month and CT-scan once in 3 months for the first year. Later, chest X-ray is ordered once in 3 months and CT-scan every 6 months for 5 years. Aggressive follow up is necessary for sarcomas.

WHEN THE RESULTS OF LAPM ARE BAD?

Results of LAPM are bad when primary cancer comes up again, when all lung nodules are not removed or when there is cancer on the outer covering of lung (pleura).  

 

DRAWBACKS OF CONVENTIONAL PROCEDURES FOR PULMONARY METASTASECTOMY 


    Here lung tissue is crushed between the jaws of stapler and the crushed segment containing metastasis is removed. Owing to the straight lines and geometric angles of the staplers, there is considerably large loss of lung tissue. LAPM does not involve such losses. Secondly, the technique is possible only for nodules on the periphery of the lung. Deeply situated lung nodules, which can easily be removed by LAPM, cannot be removed by staplers.


    This operation is done for deeply located tumours where wedge resection is not possible. Here one third or one half of lung is removed. Obviously, loss of healthy lung tissue is huge.

    SINGLE METASTATIC NODULE IN THE LUNG  CONVENTIONAL TECHNIQUES UNNECESSARILY REMOVE A PIECE OF LARGE LUNG TISSUE  LAPM REMOVES THE DISEASE AND JUST THE NECESSARY FEW MILLIMETERS OF NORMAL LUNG AROUND IT LEAVING LUNG NEARLY NORMAL 



    Even 1 centimetre deep cut in the lung using electrocautery results in considerable air leaks and bleeding. This rules out its routine use for most of the metastasectomies.


    Since it does not permit digital examination, it is incomplete in 25% of cases. It is also not possible for deeply located nodules.


    They are radio-frequency ablation, cryoablation and microwave ablation. Like VATS, they cannot accomplish complete resection in all patients. Proof of disease-free margins is also not possible.

 

SUMMARY OF ADVANTAGES OF LAPM 

  • Minimum loss of healthy lung tissue
  • Very little blood loss, no need of blood transfusion
  • Minimum air leaks, shorter duration of chest drainage
  • Short hospitalisation
  • Easy removal of deeply located tumours
  • Raw area can be sutured back leaving near normal lung contour
  • Surgery of primary cancer and lung metastasis can be done together
  • Any number or size of metastasis from one or both lungs can be removed
  • If required, operation can be repeated safely
  • Patients declared  “inoperable” and “hopeless” can be offered a chance of quality life for extended period
  • Applicable to any primary site of cancer
  • Less chances of local recurrence as no cancer cells survive at  700 degree Celsius
  • Removed cancer can be studied by pathologist
  • Minimum risk to life and minimum complication rate-1 to 2 %
  • Cosmetically acceptable
  • Very short or no ICU stay
  • Faster than conventional  techniques
  • Improves  5-year survival from 3-5% to 35-40%

 

 

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