Thoracic surgery for lung cancer: current practice and future directions

Lung cancer is a disease that is usually identified too late for treatment with curative intent. This results in a five-year survival reported to range widely from 2% to 30%. ¹ We do not regard this as acceptable in the modern healthcare era, particularly when we know that some patients can be ‘cured’ (and by that we mean long-term or sustained remission) if diagnosis is made early enough.

So why surgery for early lung cancer? Put simply, because it is usually low-risk, cost-effective with excellent patient-related outcomes and can be performed with minimal morbidity. ² There are various innovations being introduced, aimed at changing the paradigm of late presentation, high morbidity and low cure rates. This will involve a multi-pronged attack at the current pathway for diagnosis and treatment of patients with lung cancer.

We explored these issues at a recent Royal Society of Medicine and Cardiothoracic Section meeting. This and the associated series of articles explore some of the issues raised and offer hope that the future of lung cancer management will be strikingly positive in contrast to the past.

Diagnosis

Unfortunately, late presentation with an advanced stage of disease remains the commonest situation. Late disease has a poor prognosis (five-year survival for stage 3a = 36%, stage 3b = 26% and stage 4 = 0–10%). ³ However, because computed tomography (CT) scans are performed so frequently now, the ‘by chance’ finding of early lung cancer is becoming more frequent.

The fact is that for patients diagnosed with early-stage lung cancer (T1a-c N0), the probability of remission is high (five-year survival for T1a = 92%, T1b = 86%, T1c = 81%). ⁴ Despite level 1 evidence of a significant survival benefit from lung cancer screening since 2011, ⁵ it is still not widely available. ⁶ A somewhat remarkable situation! This is because of a rather odd mixture of academic, political and system resistance. Meanwhile, studies assessing the value of screening continue.

Notwithstanding the impasse – provided there is sufficient will – at some stage, screening with radiology and biomarkers should become available. This will re-characterise lung cancer as a disease with a much longer survival and the prospect of ‘cure’ by various techniques including radiotherapy as discussed by Conibear et al., ⁷ intervention as discussed by Smith and Jennings, ⁸ or surgery perhaps combined with more targeted molecular or immune-based therapies. The principle will be to destroy or remove as little functioning lung as possible commensurate with improved survival. Part of the focus will be directed to the surgical ‘margin’ as discussed by Waller. ⁹

Human resources

In the UK and elsewhere, there has been a large increase in the number of dedicated thoracic surgeons who have undergone specific training including advanced fellowships. This increase has correlated with an increase in lung cancer resections. At the same time, there has been a reduction in pneumonectomy and a fall in mortality. ¹⁰ This is thought to reflect the benefits of increased numbers of specialised thoracic surgeons. These surgeons are the result of thoughtful actions taken by the previous generation. These teams are more aggressive than before, taking on frailer patients and increasingly offering lung-conserving approaches such as sleeve resections, along with improved selection and peri-operative care.

A shortage of good surgical assistants is being addressed by low cost and highly effective robotic telescope holders such as the Freehand system which is now being used for uniportal and more standard video-assisted thoracoscopic surgery. ¹¹ A few units are also using more sophisticated and complex robotic systems.

Treatment

Patients diagnosed with lung cancer are increasingly managed by specialist multidisciplinary teams, to ensure that they receive appropriate treatment. ¹² Traditionally, surgical resection with a lobectomy or pneumonectomy offered the best chance of a cure and was offered to a relatively fit and younger population of patients.

Impaired lung function

We now know that in many patients with emphysema, there can be considerable improvement in lung function and other performance measures with smoking cessation, preoperative rehabilitation (‘pre-habilitation’) and targeted lung resection also known as lung volume reduction surgery. Depending on the disease pattern this can include excision of the lung cancer with a good surgical margin.

The calculation of predicted postoperative lung function in patients with emphysema is complicated and unreliable since many improve their lung function after treatment in a successful lung volume reduction surgery programme. ¹³ Lung volume reduction surgery is one of only three treatments which improves life expectancy in emphysema, the other two being smoking cessation and oxygen in hypoxic patients.

The impact of enhanced recovery

This is discussed more fully by Giminez-Mila. ¹⁴ The shorter discharge and other benefits arising from being able to mobilise the patient on the day of surgery and changing their expectations to one of very early discharge should not be underestimated. Part of this has come about from the availability of ambulatory chest drains systems which deliver controlled suction and being able to safely discharge patients with their chest drain in place.

Minimally invasive surgery

In terms of surgical practice for early lung cancer and selected cases of more advanced disease, there has been a major shift towards minimally invasive surgery. Video-assisted thoracoscopic surgery for lung cancer has increased, so that in many UK units, it constitutes more than half of lung cancer surgery.

Advances continue, with the goal of being even more minimally invasive such as ‘micro-lobectomy’ (small incisions coupled with a subxiphoid extraction), totally subxiphoid thoracic surgery^15,16 and even robotic video-assisted thoracoscopic surgery lung resection. The even less invasive approach of ‘operating port only’ surgery is being performed with the resected lung being removed through approximately 1-cm incisions. ¹⁶ Thoracic surgeons are even considering approaches to natural orifice surgery. ¹⁷

As compared to classical thoracotomy, proponents claim that ‘their technique’ offers to patients a combination of smaller scars, less pain, faster recovery and a reduced length of hospital stay. It is important that with these developments, the requirement for oncologically sound, R_O resection with an appropriate lymph node dissection should remain the priority over ‘surgical prowess’.

There are no contemporary high-quality trials generating level 1 evidence which compare one surgical approach over another. The pace of development is such that new techniques are being promoted and popularised via the Internet and social media with much chatter but not much analysis. With that gentle caution, we can also see that surgical numbers are increasing, older and frailer patients are undergoing surgery, a greater proportion of cases are being done by minimally invasive techniques and patient stay is becoming shorter. ¹⁸

In the absence of large randomised multi-centre trials, we are left with evidence which is of mixed quality. From this, consensus statements have been prepared, which even early in the experience supported the role and benefits of minimally invasive surgery. ¹⁹ These show that there is at least oncological equivalence between minimally invasive and open surgery and some outcomes may even be superior. Examples of this include the increased frailty and age of patients successfully undergoing thoracic surgery as well as an increased proportion of patients being able to receive adjuvant treatment in video-assisted thoracoscopic surgery groups as compared to open surgery. ²⁰ Limitations are also recognised – for example, lymph node dissection sometimes being more difficult in minimally invasive surgery, but this too is being overcome.^20–22

Surgery for more advanced disease

With an increase in the number of dedicated thoracic surgeons, we have seen resection rates rise in many jurisdictions. Part of this is about dealing better with frailty and not being ageist. In part, this also reflects increased confidence among thoracic surgeons in respect of being able to offer surgery for locally advanced disease (such as Pancoast tumours, invasion of the chest wall and sleeve resections) and after induction treatment or after relapsed disease. This includes treatment by less invasive techniques. ²³ In experienced centres, advanced surgical techniques are being performed for more locally advanced lung cancer, with the aid of adjuncts such as extracorporeal membrane oxygenation and cardiopulmonary bypass. These techniques provide a controlled environment for advanced tracheal and carinal resections and resections involving the great vessels.

The range of resections

Historically, and based on a single randomised controlled trial, lobectomy became the standard operation for non-small-cell lung cancer. In this study, some cT1 lesion patients were randomised to lobectomy or sublobar resection. There was no difference in overall survival, but the recurrence rate was higher after sublobar resection. ²⁴ This study reflects a now historical style of assessment with less detailed staging and it excluded middle lobe tumours.

Consequently, the status of lobectomy is being re-examined in new studies reviewing its position in comparison to segmentectomy and also stereotactic radiotherapy, particularly for early stage tumours. ²⁵

The importance of being able to resect less lung parenchyma and offer a lymph node dissection with minimal morbidity is relevant since it allows frailer patients to undergo surgery with more accurate staging than non-surgical techniques.

Surgery if there is more than one site of disease

This can be considered when there is more than one site of primary lung cancer or for metastatic disease to the lung. For appropriate cases of primary lung cancer, the approach of giving the ‘benefit of the doubt’ to more than one lesion rather than assuming it represents metastases with a poorer prognosis means that each site (up to a limit related to how much working lung is left behind) can be surgically treated on its own merits. This has led to patients undergoing resection from more than one site which may be more efficacious with respect to survival than a purely palliative approach.

In the case of metastasis to the lung, surgeons need to consider the biology of the primary disease (i.e. colorectal, melanoma, etc.) since disease which is aggressive is unlikely to be one in in which surgery has much of a role although as always, multi-disciplinary discussion is important. Thereafter, providing the disease is controllable at all sites, resection of disease based on total volume of lung lost may be more relevant than the number or site of lesions (which used to be the main arbiter of referral). This is a controversial area in which studies can be difficult to conduct.

Thoracic anaesthesia and enhanced recovery

Together with these surgical developments have come advances in thoracic anaesthesia and a move to enhanced recovery programmes. Anaesthetists are attempting to minimise the impact of their anaesthetic on patients, to hasten their recovery: with developments such as ‘opioid-free’ anaesthetic and non-intubated thoracic surgery; together with renewed appreciation of the positive benefit peri-operative nerve blocks have. ¹⁴ With these advances, patients are routinely being mobilised on the same day as surgery with collaboration of physiotherapists. A small number of patients undergo lobectomy as day-surgery.

Some may argue that reduced patient stay is more related with the enhanced recovery process than the actual surgical or anaesthetic technique. This is evidenced by a reduction in length of stay in both VATS and open surgical groups when enhanced recovery is followed.

Summary

If we can identify lung cancer earlier, the chance of ‘cure’ is much greater. Screening is a necessity. Defining the higher risk group and driving down charges can make this more cost-effective in addition to ‘just survival’.

Surgical advances combined with more thoracic surgeons, enhanced recovery and advanced thoracic anaesthesia have significantly extended the profile of patients deemed ‘operable’. Older and frailer patients, with poorer lung function and more co-morbidities are now being offered surgery with excellent outcomes.

Demonstration of just how far thoracic surgery with enhanced recovery has come can be evidenced by examining the successful outcomes of modern lung volume reduction surgery. Such patients, previously considered inoperable, are now a group who see some of the greatest benefits of thoracic surgery.