Should we recommend low dose computerized tomography of the

chest to screen for lung cancerGeneral Internal Medicine Grand Rounds

Dave TanakaOctober 30, 2012

Objectives

• Review previous data on lung cancer screening• Review the National Lung Screening Trial• Review current recommendations for lung

cancer screening• Each clinician should have “Talking points” for

patient discussions

Lung Cancer Facts

• Lung cancer is the leading cause of cancer death in US (worldwide)

• The American Cancer society estimates that there will be 226,160 new cases of lung cancer and 160,340 deaths in US is 2012

• Most lung cancer is diagnosed at advanced stage (40% stage IV, 30% III)

• 5 year survival 16%

Questions

• How many have had patients request lung cancer screening?

• How many have offered chest xrays as lung cancer screening?

• How many have offered chest CT scanning for lung cancer screening?

Lung Cancer screening practices of primary care physicians: results form a national survey

• 2006-2007 national survey, 962 responses, 38% no lung cancer screening, 55% had ordered CXR, 22% LDCT and <5% cytology

• 25% believed an expert group recommends lung cancer screening

• The factors that predict ordering of lung cancer screening: belief that experts recommend it or that screening tests are effective, if they would recommend screening for asymptomatic, non-smokers and if their patients had asked them about screening.

Chest xrays

• 4 RTC 6,300-11,000 patients, 1970-1980’s• No difference in lung cancer mortality in the

screening groups vs controls (this compared more frequent CXR’s because CXR was often used on regular basis for smokers)

• There were increased numbers of lung cancers found in the screened group (over diagnosis)

PLCO study

• RTC 154,901 1993-2001 age 55-74• CXR at baseline then 3 annual screens vs usual

care• F/U to max 13 years• 10% current smokers, 42% previous smokers,

11% with 1st degree relative with lung cancer• CXR screened lung cancer mortality 0.99

(0.87-1.22) vs usual care

PLCO study (NLST eligible)

• CXR 15,183 vs usual care 15,138 • CXR 60.9% male vs usual care 60.2%• CXR 52.0 pack yrs vs usual care 52.5 pack yrs• Lung cancer incidence (per 100,000 person-

yrs) CXR 606 vs usual care 608 (RR 1.00 0.88-1.13)

• Lung cancer mortality CXR 361 vs usual care 383 (RR 0.94 0.81-1.10)

PLCO study conclusions

• No benefit from CXR screening in lung cancer mortality vs usual care

• Subanalysis (NLST eligible) – no benefit from CXR screening in lung cancer mortality at 6 years (no difference at 13 years)

National Lung Screening Trial

• RTC 53,434 8/2002-4/2004 33 US MedCen• Age 55-74, smoked > 30 pack-yrs, quit within

past 15 years• Exclusions: previous diagnosis of lung cancer,

hemoptysis or unexplained weight loss > 6.8 kg (15 lbs) in preceding year

NLST

• Randomized to LDCT scan (26,722) vs CXR (26,732)

• 3 screening studies, T0, T1, T2 done at 1 year intervals

• Positive result defined as > 4mm non-calcified nodule

ResultsT0 T1 T2 Total

PositiveFalse Positive

CT scan 27.3% 27.9% 16.8% 39.1% 96.4%

CXR 9.2% 6.2% 5.0% 16.0% 94.5%

Adverse Events

Complications after diagnostic evaluation procedure after positive screening testCT scan 1.4%CXR 1.6%Major complications after diagnostic evaluationCT scan lung cancer +11.2% - 0.06%CXR lung cancer + 8.2% - 0.02%

Lung Cancer

• CT scan 1060 645 / 100,000• CXR 941 572 / 100,000

Lung Cancer Mortality

CT scan 356 247 / 100,000 1.4%CXR 443 309 / 100,000 1.7%

Absolute difference of 0.3%For every 1,000 screened there will be 14 lung cancer deaths after 3 yearly CT scans and total time of 6.5 years, 3 lung cancer deaths will be averted.

The Role of Computed Tomography (CT) Screening

for Lung CancerRecommendations from the American College of Chest Physicians and the American Society of Clinical Oncology

RECOMMENDATIONS

Note: Grade of recommendations based on modified GRADE approach (http://www.gradeworkinggroup.org)

Recommendation 1• For smokers and former smokers who are age 55 to

74 and who have smoked for 30 pack years or more and either continue to smoke or have quit within the past 15 years, we suggest that annual screening with low-dose CT should be offered over both annual screening with chest radiograph or no screening, but only in settings that can deliver the comprehensive care provided to NLST participants.

• Grade of recommendation: 2B

• Note: Pack year = the number of packs of cigarettes smoked per day multiplied by the number of years a person has smoked

Remarks for Recommendation 1• Remark 1: Counseling should include a complete

description of potential benefits and harms, as outlined the guideline (online), so the individual can decide whether or not to undergo LDCT screening.

• Remark 2: Screening should be conducted in a center similar to those where the NLST was conducted, with multi-disciplinary coordinated care and a comprehensive process for screening, image interpretation, management of findings, and evaluation and treatment of potential cancers.

Continued on next slide

Remarks for Recommendation 1, cont’d

• Remark 3: A number of important questions about screening could be addressed if individuals who are screened for lung cancer are entered into a registry that captures data on follow-up testing, radiation exposure, patient experience, and smoking behavior.

• Remark 4: Quality metrics should be developed such as those in use for mammography screening, which could help enhance the benefits and minimize the harm for individuals who undergo screening.

Continued on next slide

Remarks for Recommendation 1, cont’d

• Remark 5: Screening for lung cancer is not a substitute for stopping smoking. The most important thing patients can do to prevent lung cancer is not smoke.

• Remark 6: The most effective duration or frequency of screening is not known.

Recommendation 2

• For individuals who have accumulated fewer than 30 pack years of smoking or are either younger than age 55 or older than 74, or individuals who quit smoking more than 15 years ago, and for individuals with severe comorbidities that would preclude potentially curative treatment and/or limit life expectancy, we suggest that CT screening should not be performed.

• Grade of recommendation: 2C

Clinician-Patient Communication

• Quantify the potential benefits• Quantify the potential harms• Emphasize smoking cessation• Point to useful tools on smoking cessation,

risk of radiation exposure and calculating lung cancer risk

Future Directions/Research

Outstanding questions/suggested research• Generalizability of reported findings• Comparison of limited # of annual screenings to

potentially higher # of annual screenings• Optimum screening schedule• Cost-effectiveness studies• Randomized trials with participants of different

ages and smoking histories than in the NLST and in settings unlike those in previous studies

How NLST might apply to a patient

• Estimates are based on 2 models, one that predicts the chance of dying from lung cancer in a year and the other that predicts the chance of dying from other causes in a year.

• The models considered the person’s age, sex, smoking history and exposure to asbsetos. Both models have been studied the lung cancer (validated) and other (under predicted)

Average NLST patient

• 62 yo male current smoker, 1.5 ppd for 35 years• Deaths from lung cancer (without screening) per

1000 person 19.5• Deaths from lung cancer (with screening) per

1000 persons 15.6• Deaths averted per 1000 3.9• Persons needed to be screened for 3 y to prevent

1 death from lung cancer over 6 years - 256

Min eligible NLST participant

• 55 yo female former smoker 1 ppd for 30 years, who just quit

• Deaths from lung cancer (without screening) per 1000 person 4.0

• Deaths from lung cancer (with screening) per 1000 persons 3.2

• Deaths averted per 1000 0.8• Persons needed to be screened for 3 y to prevent

1 death from lung cancer over 6 years - 1236

High-risk NLST participant

• 70 yo current 2 ppd smoker for 55 years• Deaths from lung cancer (without screening) per

1000 person 60.9• Deaths from lung cancer (with screening) per

1000 persons 48.7• Deaths averted per 1000 12.2• Persons needed to be screened for 3 y to prevent

1 death from lung cancer over 6 years - 82

Min eligible participant by NCCN guidelines

• 50 yo male former smoker 1 ppd for 20 years, who quit 10 years ago with an occupational asbestos exposure history

• Deaths from lung cancer (without screening) per 1000 person 1.6

• Deaths from lung cancer (with screening) per 1000 persons 1.3

• Deaths averted per 1000 0.3• Persons needed to be screened for 3 y to prevent 1

death from lung cancer over 6 years - 3180

Low risk eligible participant for Sequoia Hospital lung screening

• 40 yo female former smoker 1 ppd for 10 years, who quit 15 years ago

• Deaths from lung cancer (without screening) per 1000 person 0.10

• Deaths from lung cancer (with screening) per 1000 persons 0.08

• Deaths averted per 1000 0.02• Persons needed to be screened for 3 y to prevent

1 death from lung cancer over 6 years - 35186

Harms of LDCT for lung cancer screening

• Detection of abnormalities• In review of RTC and cohort studies the

average detection of lung nodules was 20%• More than 90% were false positives• In NLST, 1.2% of patients not found to have

lung cancer underwent invasive procedure and 0.7% had thoracoscopy, mediatinoscopy or thoracotomy

Adverse Events

Complications after diagnostic evaluation procedure after positive screening testCT scan 1.4%CXR 1.6%Major complications after diagnostic evaluationCT scan lung cancer +11.2% - 0.06%CXR lung cancer + 8.2% - 0.02%

Harms of LDCT for lung cancer screening

Overdiagnosis• Previous studies suggest that CXR may have an

overdiagnosis rate of 25%• NLST show 120 excess lung cancers in the CT

scan group vs CXR but further f/u is necessary

Harms of LDCT for lung cancer screening

• Radiation exposure• LDCT 1.5 mSv per exam• Diagnostic chest CT 8 mSv, Chest CT/PET 14

mSv• Average NLST patient received 8 mSv over 3

years (screens (3) + diagnostic) and it is estimated that will cause 1 death from cancer per 2500 persons screened

Harms of LDCT for lung cancer screening

• Quality of Life• CT scan screening 88-91% reported on discomfort but

46% reported psychological distress while awaiting the results

• There may be QOL benefits from lower morbidity from advanced lung cancer but there are also potential harms due to anxiety, cost and harms from diagnostic tests for false positive scans and overdiagnosed cancers

Other considerations

• The operative mortality for lung cancer surgery in NLST was 1% in CT scan and 0.2% in CXR. This compares to 4% operative mortality seen in general population study.

• Cost effective analysis is planned and is pending

Other considerations

• Will populations with a different risk profile than NLST benefit?

• Are less frequent screening regimens effective?

• How long should screening continue?• Would a different criteria for a positive scan

provide the same benefit but at less risk of false positive / lower cost?

Conclusions

• There is no benefit from CXR screening for lung cancer

• The NLST demonstrates a lung cancer mortality benefit with 3 yearly LDCT scans and an average f/u of 6.5 years. The absolute benefit is 0.3% or 1 averted death / 320 screened

• The average rate of positive scans is 20% (90+% are false positives)

Conclusions

• The risk of major complication seen in NLST for patients not diagnosed with lung cancer undergoing diagnostic procedure is 0.06%

• The risk from radiation estimated for the average NLST participant (8mSv) is 1 cancer death per 2500 participants

My recommendation

• If after discussion of risks and benefits, I would only offer LDCT screening for individuals that meet the NLST eligibility criteria – age 55-74, smoking at least 30 pack-years, quit within previous 15 years. I would recommend LDCT for no more than 3 years.

Introduction & Context• High mortality associated with lung cancer• Most diagnoses occur at later stages• Prior to screening with low-dose computed tomography

(LDCT), no evidence that screening strategies decreased lung cancer mortality risk

• National Lung Screening Trial (NLST) – first randomized controlled trial (RCT) to show a screening benefit in people with a history of heavy smoking (e.g. smoking 1 pack a day for 30 years or 2 packs a day for 15 years)

• All screening technologies carry potential benefits and potential harms

Guideline Methodology: Systematic Review

• Guideline based on a systematic review by the American Cancer Society, American College of Chest Physicians, American Society for Clinical Oncology and National Comprehensive Cancer Network

• An Expert Panel reviewed relevant medical literature• Databases searched and data parameters

MEDLINE: 1996-April 2012 EMBASE: 1996-April 2012 Cochrane Collaboration Library: April 2012

Evidence base: Eight RCTs and thirteen cohort studies in which all subjects were screened with LDCT

Clinical Questions

• Key Question 1: What are the potential benefits of screening individuals at elevated risk of developing lung cancer using LDCT?

• Key Question 2: What are the potential harms of screening individuals at elevated risk of developing lung cancer using LDCT?

• Key Question 3: Which groups are most likely to benefit or not benefit from screening?

• Key Question 4: In what setting is screening likely to be effective?

Abbreviations: LDCT, low-dose computed tomography

Summary of the Evidence

1. The National Lung Screening Trial (NLST), a large, high quality randomized controlled study demonstrated that among adults between the ages of 55-74 who smoked at least 30 pack years, including former smokers who quit within 15 years, annual screening with low-dose CT for 3 consecutive years reduced the absolute risk of lung cancer death by 0.33% when compared to annual screening with chest radiography. (continued on next slide)

Summary of the Evidence, cont’d

1 (cont’d). This translates to 3 fewer deaths from lung cancer for every 1,000 high-risk individuals who undergo CT screening rather than screening with chest radiography and a 20% relative risk reduction. This mortality reduction was observed over a median follow up of 78 months. Another smaller randomized controlled trial of CT screening did not find a benefit when compared with no screening.

Summary of the Evidence, cont’d

2. Multiple studies have shown that screening with low-dose CT finds lung nodules in about 180 of every 1,000 individuals who undergo screening. While 95% of these nodules ultimately prove not to be cancerous, their evaluation typically involves repeat CT scanning, and sometimes requires the use of invasive procedures, including surgery. Invasive procedures carry risks, including rarely, major complications and even death.

Summary of the Evidence, cont’d

3. The reported outcomes for CT screening have been achieved in selected, high-risk, motivated study volunteers who underwent screening at centers with experience in imaging, diagnosis and treatment, using an organized process of scanning, scan interpretation and nodule evaluation. Application of CT screening to lower risk groups or outside of these settings may alter the balance of observed benefits and harms unfavorably.

Summary of the Evidence, cont’d

4. The reported benefit of CT screening is primarily from a study that compared LDCT screening to chest x-ray screening rather than no screening. Studies have not found a benefit of chest x-ray screening.

5. Extrapolated estimates suggest that the magnitude of the harm from radiation delivered by low-dose CT screening is smaller than the estimated benefit of screening individuals such as those screened in the NLST for lung cancer.