2012年6月25日 星期一

Tuberculosis - Not a Dying Disease 肺結核從來沒有消失

Pulmonary tuberculosis is an infectious disease caused by slow growing bacterial species known as Mycobacteria. The name of this germ is borrowed from its characteristics of slow growing, indolent and can present as spore keeping bacteria alive in long term in adverse temperature and humidity condition similar to fungus. The air borne ability of the mycobacteria spore give it as much infectious concern as influenza. However, the man to man transmission ability is far lower than virus. Also the amount of infectious load is much higher than virus to cause clinical disease. For example, exposure to droplet transmitted virus like measle may cause successful disease transmission if only ten or a little more viral particle is inhaled by susceptible individual. In tuberculosis, intense exposure to hundreds of spores may not end up in clinical disease. However, as mycobacteria tuberculosis is ubiquitous in most human inhabitated area. Avoidance of it is much difficult.

Tuberculosis is still endemic disease in Hong Kong. Although treatment of such disease has made so much advancement that curing this disease is now mainly an out-patient managment problem.  A few decades ago, if young men or women has been infected with tuberculosis, the treatment of such is still old fashioned resting and sunlight and good nutrition. Housing in a sanatorium or convaslescent environment is only method to prevent spread of disease in densely potpulated cities. Paradoxically this air borne bacteria has much less infectivity potential if high ceilings, good ventilation and well space out beds in room with natural ventilation.  Few staff in such sanatorium will be infected due to working environment unless the nurse or doctor has overworked too much to have low immunity.

Are healthy individual always resistant to tuberculosis?  The answer may be yes and no. For malnourished and alcoholic, reactivation of tuberculosis and primary infection is likely. But for healthy individual, reaction to latent tuberculosis may be  exaggerated causing destruction of lung or granuloma formation.  Reactivation of tuberculosis or persistent of infection may also related to hormone, age and genetic make up.

Nowadays treatment of tuberculosis is effective and comprehensive. Different class of drugs has good effect on it. Investigation to underlying immune deficiency is necessary but rarely postive in endemic area like HK. But confusion with lung cancer shadow is much of a concern too. Therefore, if lung shadow has shown poor response to antituberculosis chemotherapy, excision biopsy is necessary in high risk individual like smokers of patients with strong family history of cancer.

Hong Kong has good system of treating pulmonary tuberculosis. Chest clinic offer walk in CXR and consultation if persistent cough for more than 2 weeks.
Supervision of tuberculosis treatment ensure good compliance. Expert of tuberculosis are easily found in governemnt services.

Sometime, thoracic surgeon may encounter cases mimmicking lung cancer. Final pathology turn out to be tuberculosis. The patient may be complaining about that. However, for lesion as big as a pseudo tumour, it is essential to remove it surgically even if good response to tuberculosis is found. Because if the lesion is left, confusion with later lung pathology or causing hemoptysis or bronchiectasis change may be as harmful as cancer itself.
For fit individual removal of granuloma of destryoed lobe by tuberculosis give better quality of life. Of course, to high risk indivdual lke patient with significant coroanary disease or renal failure, option for medical treatment alone is better suited then.

2012年6月24日 星期日

Tiny Sub centimetre Lung Nodules - Risk of early Adenocarcinoma of Lung

In Hong Kong, the incidence of lung cancer is growing gradually. There is some relation to wider detection and longer life expectency. Some other factors remain unknown.  Before the Second World War, lung cancer ;as I was told by my medical teacher: is a rare disease.  The rapid development of tobacco industry co-incide with the escalating cases of Lung cancer in the West.  Thoracic surgeons who used to treat different form of infectious disease, sequealae of pulmonary tuberculosis were burdened with different forms of malignant tumour of the chest.

So the cause of lung cancer growth is definitely related to increase in smoking population, air pollution, urban life style.  Since lung cancer is potentially more lethal than other solid tumousr. In male, lung cancer is second highest (next to colon and rectum) in incidence and highest in causes of death among malignant disease. In Female lung cancer is third highest in incidence ( second to breast, colon and rectum) and highest in cause of death.  In female and now in young male, adenocarcinoma is highest is frequency.

There has been several proposal of cause of high incidence of non smoking related lung cancer in South Chinese females esp Hong Kong women.  One of this is related to kerosene stove or cooking method with exposure to incomplete combustion product in stove.  Relation to hormone and Chinese herb or aflatoxin in fermented food or nuts has also been investigated. Genetic markers also has been looked into.  No scientific proof or conclusion can be drawn after decades of study.

So screening remains the only method to detect early lung cancer.
Are all minute nodules in CT scan (low dose CT scan for lung cancer detection) needed to be removed ?
This is a difficult question and each case has to be individually assessed and considered.

Surgical risk and ease of small wound resection of the mass needed to be assessed too.

For lung nodules about 6 mm in size.  Assume the tumour doubling time is 3 month. Six month later, the volume of the tumour will be quadruple and the diameter fo the nodule will be 1.6 time larger or about 9.6 mm. A normal 5 mm cut CT scan will easily detect the enlargement of the size. Although there is no guarantee of abse3nce of distal metastases, the chance of finding metastaes for primary lung cancer size less than 1 cm is low by restrospective study of clinical cases.
So it may be safe to observe 6 mm nodule with CT scan every 6 months for 2 to 3 years.

For lung nodules larger than 9 mm in size, the chance of being pathological lesion like tumour, benign adenoma, sclerosing hemangioma, hamartoma or secondary lung tumour, granuloma is high.  From VATS experience, for peripherally situated 9 mm nodule, more than 70% can be definitely located by digital palpation on lung surface. Excisional biopsy is recommended. For patient age less than 65 without major illness or cardiopulmonary compromise, the risk of VAT lung biospy with excisional wedge resection is minimal and usually required 2 - 3 days of hospitalisation.  So I recommend early surgery for that.  For deep seated 9 mm nodule, both excisional biopsy by VATS or fine needle aspiration biopsy cytology are difficult.  I would recommend observation with 3 monthly CT scan and opt for either Fine needle biopsy if size increases or open wedge resection if patient has high risk (smoker or family history of 2 family member having cancer) of malignancy,

For non well defined nodule or ground glass appearance, I would recommend PET CT scan instead of CT scan alone because measurement of size cause confusion in vague shadow.

For definite solid nodule without characteristics of cancer, PET CT is less helpful to define the nature except for measuring the size change.  For granuloma or post infectious change, the PET value or SUV value may be elevated. For broncho alveolar carcinoma, the PET SUV value will be normal.

For lesion less than 6 mm in size, I would recommend either repeating CXR or low dose CT scan in one year time. If the nodule is persistent, work up for lung cancer risk and repeat of CT scan in 6 month time for next 2 years are recommended.

For bilateral tiny nodules, screening for primary and PET CT would be useful. Consideration for millary TB may also be needed. Infiltrative lung disease and intersitial lung disease are also required. The final conclusion will depend on the VAT lung biopsy and resection the dominant nodule ( if present) for histology

The above recommendation is primarily subjective impression a, taking into consideration of guideline from European Society of Respirology 2010 guidelines and American College of Chest Physicians 2006 reommendation for solitary lung nodules. I am experienced cardithoracic surgery with more than 24 years of experience in public hospitals in Hong Kong and private hospital. I welcome any queries or question. Phone: 3160 8865 Dr Chung Shiu Shek

2012年6月20日 星期三

Non invasive Surgery - A myth or a new paradigm 非侵入性治療

There is a saying or "cliche" that Chinese medicine is good at chronic disease modulation and health maintainence and Western medicine is best suited for surgical condition like tumour  and/or obstruction, and traumatology.  Nowadays, surgical condition is more and more treated by catheter or percutaneous manipulation method.  Previous school of thinking on big incision and wide exposure has been out of favour and prevents patients' acceptance.  The one and may be the only one question that patient want to ask about is whether there is minimally invasive surgery option available.

It appears that all invasive procedure or wide wound exposure is wrong and not serving patients good.
I may be over exaggerating the vision and trend of going minimally invasive and conservative in treating most mechanical or surgical disease.

However, as surgeon witnessing the evolution of minimally invasive approach in various conditions. I believed that the patient may have an incorrect idea of how minimally invasive surgery develops and contributes to expansion the treatment armentarium. So , the new paradigm of going minimally invasive is not a new invention but a means to perfect the appraoach to meet the old well established target.  Should the operative target remain far from what minimally access approach can meet, old approach is as effective and the only soloution to be the best approach and fail safe approach.

Surgery includes ablation and reconstruction. In fact, the analogy of plumbers and surgeon is particularly intuitive as lot of lesions will be dealing of obstruction of tubular structure. Either replacing the entire passage with conduit or bypass or recannulating the stenotic part with stent or expansile scaffolding device will solve the condition.
So the use of stent and supporting stenting scaffold device will be universal in many disease system. For solid tumour in the body, so far ablation method using open appraoach stood the test of time. Complete removal leaving good margin of at least 5 mm or if not possible 3 mm clearance ensure minimal chance of local recurrence.  Any other compromise in margin or breach across the tumour capsule or surronding tissue will deprive patient only chance of survival.  Internal stenting may be used as temporarily a salvage option or pre operative optimisation. Radical removal usually still need bigger wound.  For complex reconstruction, open surgery still is the gold standard.

Secondly, the time  spent on the surgery and learning curve involved in mastering the necessary skill is the bar before contempating new approach. For example, in robotic surgery requiring wide movement of target operation site, e.g. removing a lung tumour. The time spent on setting up the robotic arms and concentrating on relevant structure tilt the balance favoring traditional Thoracosocpic resection rather than Robot assisted minimally invasive surgery.  Learning curve is indeed the major concern for both the surgeon and the patient.  For patient demanding the less practiced minimally invasive surgery, he or she must do good research to go to surgeon with good track record in other new surgical appraoach so that the relative time for learning cujrve is small.

Risk of bleeding in going minimal invasive.  The extent of surgery dose not become smaller even if minimally invasive surgery. However, paradoxically, minimally invasive surgery to some extent increase the safety margin because hemostasis is better and picture is clear on optically ideal magnified view. Good surgical tecnique can circumvent the absence of tactile sensation and degree of freedom of long through the hole instrument.  Yet, from time to time. Heavy bleeding as a result of small wound surgery approach is never short of examples.  Years and years and time after time. Patients' interest is at risk for unjustified minimally access for complex surgery or absence of good surpervision and help in steps moving away from conventional surgery. No compromise of safety should be allowed for surgeons choosing small wound or non invasive approach.

Pooling of cases may be difficult for less common patholgy. In another words, minimally invasive surgery may not be vivable if the encountered pathology is rare or the referral basis of that centre is small. Like so mnay audit report, in rare pathology, the surgical outcome is in direct proportion to the case volume.  But in ususal pathogy like gallstone or hernia., the difference between small centre and big referral centre is negligible.

In short, I really support the current trend of going minimally invasive in every possible operation. But still I believe it needs right time, right place and last but not least the right occasion (patient and skill mix). Otherwise, I believe in the old saying that it is safer to detour a usual path to guarantee arrival than to risk for new route. And, old dogs usually learn new tricks slow but can play it safe after skill acquirment.