Screening for lung cancer

Dr David Simcock discusses the role of EBUS in diagnosing lung cancer.

Coloured CT scan showing a lung biopsy being performed
Coloured CT scan showing a lung biopsy being performed

Lung cancer is the leading cause of cancer-related death and the second most common form of cancer overall. Its incidence in men is now starting to decline, but the incidence in women is increasing.1-3

Smoking prevalence is falling in the developed world, but increasing in the developing world, where the burden of the disease is predicted to rise considerably.1-3

Endobronchial ultrasound

Endobronchial ultrasound (EBUS) and transbronchial needle aspiration of mediastinal and hilar lymph nodes allow the rapid diagnosis and staging of lung cancer in a single, short day-case procedure, carried out under conscious sedation.

EBUS's diagnostic sensitivity is superior to surgical mediastinoscopy, previously considered to be the gold standard in staging the mediastinum and assessing resectability.4

EBUS is recommended by NICE as the first-line investigation for the diagnosis of suspected lung cancer.5

The identification and targeting of specific gene mutations, such as EGFR and anaplastic lymphoma kinase, in non-small cell lung cancer (NSCLC) cells allows individualised molecular therapy.

Drugs that inhibit EGFR are used first line and in preference to standard chemotherapy in those with advanced NSCLC, with improvements in progression-free survival.6

Surgeons are now performing minimally invasive lobectomies with a video-assisted thoracoscopic approach, with lower complication and mortality rates, allowing older, more frail and unwell patients to undergo curative surgery.7,8

Long-term survival

Despite these advances, the overall long-term survival in patients diagnosed with lung cancer is poor, with fewer than 10% alive at five years.9

Lung cancer symptoms develop late and at initial presentation, more than 75% of patients have inoperable disease and are treated palliatively.10 Other common cancers, such as breast, prostate and bowel, have well-established and successful screening programmes. Screening permits early diagnosis before the onset of symptoms and patients diagnosed with these cancers can expect an excellent prognosis and good five-year survival.

Pros and cons of lung cancer screening

Pros

  • - Lung cancer is very common
  • - Incidence is rising in women
  • - Long-term survival is poor
  • - Early diagnosis improves prognosis and survival
  • - EBUS
  • - Safe in early stage tumours

Cons

  • - High rates of false positive
  • - Overdiagnosis
  • - Cost-effectiveness

The role of screening

In 2011, the results of the US-based National Lung Screening Trial (NLST) were published, which addressed screening patients for lung cancer.11

This trial randomised 53,454 patients aged 55-74 with a 30 pack-year smoking history (or ex-smoker within the past 15 years) to receive screening with a chest X-ray or low-dose CT scan, at yearly intervals for three years.

While more than 90% of screening abnormalities, from both groups, were benign 'false positives', there was an overall 20% relative reduction in death in the low-dose CT arm (p=0.004).

A criticism of this and previous lung cancer screening trials is that most patients with abnormal radiology undergo invasive investigations which can potentially cause harm.

The authors of the NLST reported that only 0.08% of all 'false positive' patients investigated for suspected cancer experienced a major complication as a result.11

There is also the possibility that screening leads to 'overdiagnosis' in identifying lung cancers that might never lead to symptoms or cause morbidity and mortality.

Questions remain regarding the cost-effectiveness of such a screening approach, where the money could otherwise be spent on smoking cessation and disease prevention.

The latest evidence for lung cancer screening shows this to be a safe way to identify early-stage tumours, with the potential to save lives in a targeted patient population.

This represents a major step forward in the approach to lung cancer, when efforts to identify measurable biomarkers in these patients remain disappointing and unavailable.

It remains to be seen if a national lung cancer screening programme is implemented in the UK to complement other recent advances in managing this common disease.

  • Dr Simcock is consultant respiratory physician, The London Clinic and The London Chest Hospital

References

1. Jamal A, Siegel R, Xu J et al. CA Cancer J Clin 2010; 60: 277-300.

2. Cancer Research UK. www.cancerresearchuk.org/cancer-info/cancerstats/types

3. Centers for Disease Control and Prevention. MMWR Morb Mortal Wkly Res 2009; 58: 1227-32.

4. Ernst A, Anantham D, Erberhardt R et al. J Thorac Oncol 2008; 3: 577-82.

5. NICE. The diagnosis and treatment of lung cancer. CG121. London, NICE, April 2011.

6. Rosell R, Carcereny E, Gervais R et al. Lancet Oncol 2012; 13: 239-46.

7. Cattaneo SM, Park BJ, Wilton AS et al. Ann Thorac Surg 2008; 85: 231-5.

8. Whitson BA, Groth SS, Duval SJ et al. Ann Thorac Surg 2008; 86: 2008-16.

9. Cancer Research UK. www.cancer researchuk.org/cancer-info/cancerstats/types/lung/survival/#one

10. Walters S, Maringe C, Coleman MP et al. Thorax 2013; 68: 551-64.

11. The National Lung Screening Trial Team. N Eng J Med 2011; 365: 395-409.

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