Pulmonary

 

tracheal tumours

Epidemiology and Aetiology

Primary tumours of the trachea are quite rare, one true primary tumour occuring for every 140 bronchogenic carcinomas. (Yang KY, Chen YM, Huang MH, Perng RP: Revisit of promary malignant neoplasms of the trachea clinical characteristics and survival analysis. In: Jpn J Clin Oncol (1997 Oct) 27(5):305-9). In fact the trachea is more commonly invaded by tumours of surrounding structures (bronchogenic, laryngeal, oesophageal and thyroid) more often than true primary tumours occur. For primary squamous carcinoma, like other squamous tumours of the upper aero-digestive tract, tobacco smoke is the main recognised carcinogen. Such tumours tend to occur in older patients. The tumours of intermediate malignancy, adenoid cystic and carcinoid are of unknown aetiology. The rarer tumours are so uncommon that aetiological factors cannot be identified.

Pathology

Primary tumours can arise from any of the tissues in the wall of the trachea and these can vary from their benign forms to the corresponding malignant sarcoma. Therefore papilloma, leiomyoma, chondroma, schwannoma, paraganglionoma, melanoma, rhabdomyosarcoma, mucoepidermoid, adenocarcinoma and small cell carcinoma have all been reported. The commonest tumours are adenoid cystic carcinoma, squamous carcinoma and carcinoid.

Adenoid cystic carcinoma

This tumour, previously termed "cylindroma", is of intermediate malignancy. In large tertiary referral surgical centres in the USA it tends to be the commonest tumour (40.4% at Massechssets General Hospital [Mathisen], 36% at the Mayo Clinic [Houston et al], 73% at Memorial Sloan Kettering [Hajdu et al]). However in Japanese and European series squamous tumours predominate. It has an even age distribution throughout adulthood from 20 to 70 years of age. It tends to displace local tissues rather than invade them and while lymph node metastases are uncommon, submucosal extension and lymphovascular invasion make the limits difficult to ascertain.

Squamous

Squamous tumours accounted for between 35% [Mathisen] and 83%(Cheung Ay: Radiotherapy for primary carcinoma of the trachea. Radiother Oncol (1989 Apr) 14(4):279-85) The peak incidence in a surgical unit (Mathisen) is between 50 and 69 tears of age. Squamous lesions may be discrete and polypoid though a field change may occur over a length of trachea. Node metastasis and incasion of mediastinal tissues are common features. This may explain the disparity of tumour types reported in surgical and radiotherapy series.

Carcinoid

Carcinoid tumours may occur anywhere within the tracheo-bronchial tree. They account for approximately 5% of primary tracheal tumours. Like carcinoids elsewhere in the bronchial tree they can vary from benign to frankly malignant behaviour. They tend to be slow growing and can have long term survival with local resection despite close surgical excision margins.

Presentation

Tracheal tumours all have a similar pattern of symptoms. They usually present with vague respiratory symptoms such as cough, haemoptysis and shortness of breath on exertion. More specific symptoms which may localise the cause include stridor, increased sputum production and recurrent chest infections. Because of its insidious development a misdiagnosis of asthma is not uncommon.

Examination

Examination may confirm the stridor though this may only be evident during increased respiratory effort. Supra-clavicular nodes may also be apparent. Otherwise the examination would depend on whether there was concurrent chest infection.

Diagnosis and Staging

On plain X-ray it is possible to see tracheal narrowing but few tumours are picked up on standard chest X-rays till after the diagnosis has been made by other means. It is usually not possible to determine whether it is due to intrinsic or extrinsic tumour.

Diagnosis is usually made at bronchoscopy. Though this is possible with the flexible bronchoscope, better control of the airway can be obtained using the rigid scope. This is particularly important when taking biopsies as bleeding may convert a compromised airway into a complete obstruction. Debridement, laser ablation and other pre-surgical evaluation are also possible via the rigid scope. It is important to exclude another tumour of the bronchial tree at this stage.

CT will outline the local tumour and any invasion of local tissues. The CT should be continued through the lung fields, a common site of metastasis or synchronous primary tumour of the lung. Scanning of the upper abdomen will reveal metastases to the liver and adrenals. As bone is also a common site of metastasis bone scan should be considered in patients with bone pain or raised alkaline phosphatase.

Treatment

The aims of treatment in tracheal tumours are twofold: obtaining a patent airway is the primary objective with cure a secondary concern. With the development of improved surgical and anaesthetic techniques in the last 30 years surgical resection has become a safe procedure and therefore has become the main treatment modality. However, only one third of patients presenting to a non specialist hospital will be suitable for resection, either due to advanced local disease or because of co-morbidity. Such patients may respond to laser ablation, intubation, stenting and palliative radiotherapy. Photodynamic therapy has been used with some success in early tumours. (Kato H, Okunaka T, Shimatani H.: Photodynamic therapy for early stage bronchogenic carcinoma: In: J Clin Laser Med Surg (1996 Oct) 14(5):235-8)

Surgery

All benign tracheal tumours should be resected if the patient is otherwise fit for surgery. Adenoid cystic tumours can have long survival even without complete excision. However, squamous tumours, like other bronchogenic squamous tumours have a poor prognosis unless excised with clear resection margins.

Anaesthetic considerations.

Because of the specialist anaesthetic techniques needed during tracheal resection these procedures should only be performed in a specialist unit with experience in this area. Obstruction of the trachea by endo-luminal tumour may prevent insertion of an endo-tracheal tube. In such circumstances the tumour may need to be debulked using laser or piecemeal debridement via rigid bronchoscope as a preliminary to the main resectional procedure.

As most resections involve a cylindrical resection of the tumour division of the airway is an intricate part of the surgical procedure. It is usually not possible to perform such resection and re-anastomosis with a standard endo-tracheal tube. Sometimes it is possible to use a narrow ET tube but CO2 retention is a problem if the calibre of tube is small. It is possible to use the "jet ventilation" technique using a cannula less than 3mm in diameter. CO2 diffuses out through the open distal trachea. The simplest technique is to withdraw the ET tube to allow the distal tracheal incision and replace it with a sterile armed tube placed directly into the distal trachea through the operative field. The standard ET tube can be replaced after placement of posterior sutures.

Surgical considerations

Tumours of the proximal trachea can be approached through a "collar" cervical incision. If the tumour extends to the mid trachea the sternum can be divided to produce a "T-shaped" incision. If necessary a trans-pericardial approach will give access to the distal trachea. Alternatively a lateral incision can produce a "trapdoor" into the right pleural cavity giving access to the distal trachea. Tumours of the distal trachea and carina are usually performed via a right thoracotomy.

The procedure usually entails resection of a cylinder of trachea including the tumour and a margin of normal mucosa. It is only possible to excise 2cm of the trachea without some form of release procedure. Localised mobilisation of tissues can result in tracheal release but at the expense of the tracheal blood supply. Anastomotic ischaemia leads to dehiscence of the reconstruction or later stenosis and is to be avoided. Supra-hyoid or laryngeal release can extend the tracheal resection to 4.5cm. The aortic arch prevents extensive distal release but it is possible to dissect the right hilum and release both inferior pulmonary ligaments via a median sternotomy or bilateral thoracotomies. A maximum of nearly 7cm of trachea can then be excised in a thin patient with good neck flexibility, a combination more usually found in the young patient with a congenital stricture or benign tumour than the elderly patient with carcinoma.

Despite modern techniques operative mortality in the region of 10% is to be expected because of the elderly population with substantial co-morbidity. (Regnard JF, Fourquier P, Levasseur P.: Results and prognostic factors in resections of primary tracheal tumors: a multicenter retrospective study. The French Society of Cardiovascular Surgery. J thorac Cardiovasc Surg (1996 Apr) 111(4):808-13;discussion 813-4)

Chemotherapy

There is very little experience with chemotherapy for tracheal tumours. Extrapolating from the experience of laryngeal and bronchogenic tumours it is probable that squamous tumours are responsive to chemotherapy which may therefore have a role as an adjunct to surgery. However, it is unlikely that cures will be obtained with current chemo-therapeutic drugs.

Radiotherapy

Both adenoid cystic carcinoma and squamous tumours are radiosensitive. (Other malignant tumours may also be radiosensitive but there is no large experience.) Because margins are often compromised in tracheal resection the Massachussets General Hospital group generally recommend routine postoperative radiotherapy to the area of resection (45 to 65 Gy). There are no randomised studies of radiotherapy as the primary treatment with curative intent. The Massachussets General Hospital experience suggests that, when compared to radiation alone, the combination of surgery and radiation results in a tripling of the median survival. For Adenoid cystic carcinoma the survival benefit is even greater (Mathisen et al). Some series have shown that when it has been possible to deliver a dose greater than 50Gy a small number of cures are possible following radiotherapy alone. (Mornex F, Cocquard R, Danhier S, Maingon P, El Husseini G, Van Houtte P: Role of radiation therapy in the treatment of primary tracheal carcinoma. In: Int J Radiat Oncol Biol Phys (1998 May 1) 41(2):299-305). Tracheal tumours are readily amenable to brachytherapy.

Radiotherapy, especially at effective doses is not without its morbidity. Tracheal stenosis, necrosis and abscess formation have all been reported.

Prognosis

Early stage tumours have a good prognosis if complete surgical clearance is achieved. For adenoid cystic carcinoma the five year survival is in the order of 73% but is lower for squamous carcinoma, 47%. Interestingly, while incomplete resection is almost universally fatal in squamous tumours, in adenoid cystic tumours longterm survival can be obtained even with positive resection margins (Regnard) . For radiotherapy, even at doses in the order of 60 Gy the five year survival is rarely above 20%. Second tumours of the upper aero-digestive tract are a common cause of late mortality.

Direct extension from other tumours

All the following tumours may involve the trachea causing obstruction

  1. Bronchogenic

  2. Laryngeal

  3. Oesophageal

  4. Thyroid

Malignant tracheo-oesophageal fistula

  1. Direct closure

  2. Resection pulmonary/oesophageal

  3. Chemotherapy (radical in Hodgkin’s etc.)

  4. Radiotherapy

  5. Radiation

  6. Stenting/intubation - doesn’t work well after cervical anastomosis. +/- tracheostomy

 

Factfile

  1. Tracheal tumours are rare compared to other airways tumours

  2. Common tumours are adenoid cystic, squamous and carcinoid.

  3. While adenoid cystic and carcinoid are amenable to surgical excision, squamous carcinomas are frequently locally advanced and, occuring in an older age group, are frequently inoperable.

  4. Adenoid cystic and squamous tumours are radiosensitve but cures are uncommon without resection.

  5. The role of chemotherapy has yet to be established

  6. Laser ablation, photodynamic therapy and brachytherapy all have a role to play.

 

References

  1. 1.Yang KY, Chen YM, Huang MH, Perng RP: Revisit of promary malignant neoplasms of the trachea clinical characteristics and survival analysis. In: Jpn J Clin Oncol (1997 Oct) 27(5):305-9

  2. 2.Hajdu, S.I. et al,: Carcinoma of the trachea. Clinicopathological study of 41 cases. Cancer 25:1448, 1970

  3. 3.Houston, H.E.et al.: Primary cancers of the trachea. Arch. Surg. 99:132,1969

  4. 4.Mathisen D.J. Tracheal Tumours. In Chest Surgery Clinics of North America, Vol 6, No 4 November 1996 875-898. Faber LP Consulting Editor.

  5. 5.Mornex F, Cocquard R, Danhier S, Maingon P, El Husseini G, Van Houtte P: Role of radiation therapy in the treatment of primary tracheal carcinoma. In: Int J Radiat Oncol Biol Phys (1998 May 1) 41(2):299-305

  6. 6.Cheung Ay: Radiotherapy for primary carcinoma of the trachea. Radiother Oncol (1989 Apr) 14(4):279-85

  7. 7.Kato H, Okunaka T, Shimatani H.: Photodynamic therapy for early stage bronchogenic carcinoma: In: J Clin Laser Med Surg (1996 Oct) 14(5):235-8

  8. 8.Regnard JF, Fourquier P, Levasseur P.: Results and prognostic factors in resections of primary tracheal tumors: a multicenter retrospective study. The French Society of Cardiovascular Surgery. J Thorac Cardiovasc Surg (1996 Apr) 111(4):808-13;discussion 813-4