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Should We Screen for Lung cancer?

Full article by Palak Shah

SummaryFull ArticleReferences
Population Screen- The aim of secondary disease prevention and population screening is to identify disease at an early stage. Screening is usually offered to high -risk individuals in order to catch a disease and treat it before it progresses. The United Kingdom Lung Cancer Screening (UKLS) Trial has recruited 4000 people aged 50-75 so far who are at high risk of developing lung cancer3 . Patients are either allocated to CT-scan screening or no screening3 . Current smokers in both groups are offered smoking cessation services. The use of follow-up questionnaires and a confidential medical record review were also used to identify potential cases3 .

In 1968, Wilson and Jungner4 described a set of decision-making criteria to be applied before implementing a populationscreening programme. Given that resources are limited and screening is labour intensive and costly, a screening tool must be deemed to have a significant impact on overall disease incidence. The criteria are applied to the lung cancer-screening program below.

1)Is the condition an important health problem?

2)Is there an accepted and effective treatment for the recognised disease?

3)Are there diagnostic facilities available?

4)Does the condition have a recognised latent or early symptomatic stage?

5)Is there a suitable and acceptable test/examination/procedure available?

6)Is the natural history of the condition known?

7)Is there an agreed policy on who constitutes a ‘case’ for treatment?

8)Is the programme economically viable?

9)Is the programme a continuing process?

Conclusion-Aside from the high cost of screening, there are also issues arising out of false positive/negative results. No test is 100% accurate and reliable, and screening isn’t any different. In presenting false positive/negative results to patients, we must consider that we could be causing psychological harm, or in a worse scenario, allowing the progression of the disease. Nevertheless, a clear benefit of screening is that it could potentially reduce the number of deaths from lung cancer, especially since death from lung cancer is preventable. Low dose CT scans have a very low risk of causing complications so the patients are unlikely to suffer any physical side effects.

Lung cancers are broadly divided into the following categories based on the histological appearances of the cells seen within the tumour1:

Overview of Lung Cancer

 

 Population Screening

“Screening refers to the use of simple tests across an apparently healthy population in order to identify individuals who have risk factors or early stages of disease, but do not yet have symptoms” – WHO2

The aim of secondary disease prevention and population screening is to identify disease at an early stage. Screening is usually offered to high -risk individuals in order to catch a disease and treat it before it progresses.

The United Kingdom Lung Cancer Screening (UKLS) Trial has recruited 4000 people aged 50-75 so far who are at high risk of developing lung cancer3 . Patients are either allocated to CT-scan screening or no screening3 . Current smokers in both groups are offered smoking cessation services. The use of follow-up questionnaires and a confidential medical record review were also used to identify potential cases3 .

In 1968, Wilson and Jungner4 described a set of decision-making criteria to be applied before implementing a populationscreening programme. Given that resources are limited and screening is labour intensive and costly, a screening tool must be deemed to have a significant impact on overall disease incidence. The criteria are applied to the lung cancer-screening program below.

1. Is the condition an important health problem?

Lung cancer is the second most common cancer in the UK accounting for 13% of all new cases5 . The crude incidence rate is 77 in 100,000 males and 61 in 100,000 females5 . Unfortunately, most patients have a poor prognosis at their time of diagnosis; the average 12-month survival is 32%, average 5-year survival is 10% and average 10-year survival is 5%5 . Staging at diagnosis is the most important indicator for prognosis. Unfortunately, most patients are asymptomatic until they develop advanced or metastatic disease; an effective screening tool could have a significant impact on average survival after diagnosis.

2. Is there an accepted and effective treatment for the recognised disease?

Treatment for lung cancer depends on the histological diagnosis and TNM staging. Surgery is offered for early stage nonsmall cell lung cancer (NSCLC). In certain patients with adequate lung function and early stage NSCLC, high-dose radiotherapy or continuous hyper-fractionated accelerated regimens (CHART) provides a good alternative to surgical resection with similar outcomes1 . Adjuvant chemotherapy or radiotherapy can improve NSCLC. Adjuvant chemotherapy with cisplatin combined with paclitaxel or gemcitabine can be given for 12 weeks1.There are also newer agents that inhibit epidermal growth factor receptors and tyrosine kinases in adenocarcinoma, which can improve outcomes in certain patients1 . Endobronchial irradiation is useful for the treatment of both intraluminal tumours and malignant extrinsic compression1 . An advantage of this technique is that radiation dose falls rapidly with distance from the source hence, minimising damage to adjacent normal tissue. Tracheobronchial stents are available for insertion into strictures caused by a tumour or when there is weakening or collapse of the tracheobronchial wall1 .

3. Are there diagnostic facilities available?

CT indicates the extent of the disease and is the key diagnostic tool in the trial. Imaging includes the liver and adrenal glands which are common sites for metastases. The International Association for the Study of Lung Cancer (IASLC) has devised the most widely used staging definitions based upon CT imaging of tumour size (T), nodal involvement (N) and metastases (M). This is known as ‘TNM staging’ of cancer6 . Using CT criteria, lymph nodes that are less than 1 cm in diameter are not considered to be enlarged but may still contain malignant cells. With increasing size, the positive predictive value of CT in detecting malignant nodes increases.

4. Does the condition have a recognised latent or early symptomatic stage?

Non-small Cell Lung Cancer Stages

Small Cell Lung Cancer Stages1:

  • Limited disease – cancer has not spread beyond the lung
  • Extensive disease – cancer has spread beyond the lung

5. Is there a suitable and acceptable test/examination/procedure available?
Currently, yes. Every participant is asked to attend a recruitment centre where they watch a DVD, be required to give
informed consent, undertake a lung function test, and provide a sample of blood, sputum and buccal scrape3.
They also complete a lifestyle and psychosocial questionnaire and are then allocated to the CT scan group or the non-CT scan group.

Scans are initially read by the Consultant Radiologist at the appropriate hospital – Papworth and Liverpool Heart & Chest Hospitals. After which, the scan images are then sent to the Royal Brompton Hospital in London to be read by a second Consultant Radiologist. Once a consensus is reached, the scan results are uploaded onto the UKLS database3.
A copy of the results letter is sent to the participants’ GPs for information. Any clinically significant incidental findings are also reported back to the GP so they can follow up as appropriate.

Two weeks after receiving the scan results the participants receive a psychosocial questionnaire in the post to be
completed and returned to the UKLS team.
6. Is the natural history of the condition known?
Yes. The more common presenting features of lung cancer are cough, breathlessness, haemoptysis and chest pain.
Bronchial carcinomas commonly spread to mediastinal, cervical and even axillary or intra-abdominal nodes. This is in addition to; the liver, adrenal glands, bones and brain, which are also frequent sites for metastases. Non-metastatic extrapulmonary manifestations of bronchial carcinomas are normocytic anaemia, thrombocytosis, clubbing and HPOA (Hypertrophic pulmonary osteoarthropathy)1.
7. Is there an agreed policy on who constitutes a ‘case’ for treatment?
There are clear outlines for what constitutes a case3:
End of screening – no abnormality found
Repeat scan in 12 months – nodule 3 mm to 4.9 mm
Repeat scan in 3 months – nodule 5 mm to 9.9 mm
Referral to multi-disciplinary team– nodule 10 mm or above
8. Is the programme economically viable?
Unfortunately the program is not economically viable. Mass population screening such as that carried out for bowel and
breast cancer, is unfeasible for lung cancer specifically because of the cost. However, focusing resources on high-risk
groups is a more cost-efficient approach. Screening could be of particular use in heavy smokers, as their risk of developing
lung cancer is marginally higher. In screening this cohort, we could potentially reduce the cost of treating advanced-stage
lung cancer and prolong patient’s lives.
9. Is the programme a continuing process?
Follow-up of both groups will continue for 10 years via the Health & Social Care Information Centre from whom data on
deaths and cancers diagnosed is received. Hospital Episode Statistics (HES) data on all participants is also considered.
Conclusion
Aside from the high cost of screening, there are also issues arising out of false positive/negative results. No test is 100% accurate and reliable, and screening isn’t any different. In presenting false positive/negative results to patients, we must consider that we could be causing psychological harm, or in a worse scenario, allowing the progression of the disease.
Nevertheless, a clear benefit of screening is that it could potentially reduce the number of deaths from lung cancer, especially since death from lung cancer is preventable. Low dose CT scans have a very low risk of causing complications so the patients are unlikely to suffer any physical side effects.

1. Parveen Kumar, Michael Clark. Kumar and Clark’s Clinical Medicine. 8th ed. Spain: Elsevier, 2012.
2. Murad Ruf, Oliver M. Diagnosis and Screening: Principles, methods, applications and organisation of screening for early
detection, prevention, treatment and control of disease. 2008. http://www.healthknowledge.org.uk/public-health-textbook/diseasecausation-diagnostic/2c-diagnosis-screening/principles-methods-applications
(accessed 18/12/2015).
3. UK Lung Cancer Screening Trial. What is the UKLS? 2012. https://www.ukls.org/index.html (accessed 18/12/2015).
4. Jeannette Naish, Patricia Revest, Denise Syndercombe Court. Medical Sciences. China: Saunders Elsevier, 2013.
5. Cancer Research UK. Lung cancer statistics. 2012. http://www.cancerresearchuk.org/health-professional/cancerstatistics/statistics-by-cancer-type/lung-cancer#heading-Zero
(accessed 18/12/2015).
6. Saeed Mirsadraee, Dilip Oswal, Yalda Alizadeh, Andrea Caulo, Edwin JR van Beek. The 7th lung cancer TNM classification and
staging system: Review of the changes and implications. World Journal of Radiology 2012;4(4).

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