Fulfilling the Potential of Cancer Prevention and Early Detection (2003) / Chapter Skim
Currently Skimming:
7. Adopting New Technology in the Face of Uncertain Science: The Case of Screening for Lung Cancer
7. Adopting New Technology in the Face of Uncertain Science: The Case of Screening for Lung Cancer
Pages 259-293
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 259... ...
Fiveyear sur-vival rates remain less than 15 percent, changing little over the past 30 years (Travis et al., 19951. While lung cancer is mostly preventable through avoidance of tobacco products, smokers, health care providers, and scientists have unsuccessfully tried other preventive approaches, such as screening for early disease with chest radiographs and sputum cytology (secondary prevention)
|
From page 260... ...
scan has renewed hope for finding an early detection method that can reduce mortality from lung cancer (Brice, 2000~. Promising preliminary studies report that spiral CT scans can detect lung cancers at a smaller size than can chest radiographs (Henschke et al., 1999; Henschke et al., 2001; Sobue et al., 2002; Sone et al., 2001; Swensen et al., 2002~.
|
From page 261... ...
Using a historical perspective, we review the lessons learned from past attempts to assist individuals, clinicians and policy makers in making decisions on the use of lung cancer screening technology despite the uncertainty of its effectiveness. SCREENING FOR LUNG CANCER BY CHEST RADIOGRAPHY AND SPUTUM CYTOLOGY In the early 1950s several researchers noted that "X-ray surveying" of the population detected lung cancers in asymptomatic individuals (Lilienfeld, 1966)
|
From page 262... ...
et al., 19f Design Uncontrolled Uncontrolled Uncontra prospective study prospective study prospect) Population and Number Screeneda 14,607 males ages 45 6,136 males ages 1,871,37 and older 45 and older radiograE Screening Interval and Method 6-month chest 6-month chest Annual c radiographs and radiographs radiograE sputum cytology Incidence Rate 0.52 percentb 2.3 percent 10.3 case (per 1,000 person-years)
|
From page 263... ...
(Wilde, 1989) led Uncontrolled Uncontrolled Controlled Controlled re study prospective study prospective study prospective study prospective study Les ages 1,871,374 67,400 males Screened group, Screened group, 41,532; der radiographs ages 45 and 29,733; control control group, 102,348 older group, 25,311 males males ages 40 and older chest Annual chest 6-month chest 6-month chest Screened group, 6-month hs radiographs radiographs radiographs chest radiographs; control group, 18-month chest radiographs it 10.3 cases/100,000 1.4 percent Screened group, Screened group, 0.9 radiographs 1.1 cases; percent; control group, control group, 0.65 percent 1.0 case 193 cases 147 cases Screened group, Screened group, 374 101 cases; cases; control group, control group, 667 cases 77 cases 20.6 percent 27 percente Screened group, Screened group, 14 15 percent; percent; control group, control group, 8 percent 6 percent t 56 percent 56 percent Screened group, Screened group, 28 44 percent; percent; control group, control group, 19 percent 29 percent t 43.6 percent 47 percente Screened group, Screened group vs.
|
From page 264... ...
The landmark randomized controlled screening trial the Health Insurance Plan of New York, which studied breast cancer was not started until the mid1960s (Shapiro, 1997~. Although most of the early lung cancer screening studies used chest radiography as the principal screening test, the VA study also evaluated sputum samples as another method for the detection of cancer.
|
From page 265... ...
Finally, postoperative death rates were high, approaching 30 percent in the Philadelphia Neoplasm Research Project study. Randomized Controlled Trials of Chest Radiographic and Sputum Cytology Screening Building on the earlier studies, the NCI sponsored three randomized controlled trials of lung cancer screening in the 1970s: the Johns Hopkins Lung Project (the Hopkins study)
|
From page 266... ...
Number of Stage 1 Cancers Detected 5-Year Survival Rate for All Stage 1 Diseaseb Percentage of All Cancers Resected Cancers Detected by Sputum Cytology Alone Number of Second Primary Lung Cancers Comments I: 26 C: 16 90 percent I: 69 percent C: 42 percent 11 2 postoperative deaths I (4,968)
|
From page 267... ...
: CXR and SC C (10,233) : the control cases in the Hopkins and Memorial studies Overall: 7.1 I: 7.6 C: 6.2 I: 160 C: 63 Hopkins/Memorial I: 55 percent; Mayo group: 40 percent; Hopkins/Memorial C: 35 percent Overall: 45 percent Overall: 105 I: 81 C: 24 80 percent I: 76 percent C: NRC 37 21 All enrollees received CXR and Sputum cytology Overall: 3.0 Overall: 19 Overall: 26 percent Overall: 5 NR 33 percent NR NR 3 postoperative deaths; 28 surgeries for nonmalignant lesions bThese survival rates reflect those that were resected, not all stage I disease.
|
From page 268... ...
. CXR = chest radiography; SC = sputum cytology.
|
From page 269... ...
: CYR and SC C (4,968) : CXR Mayo Lung Project, 1971-1976 (Fontana et al., 1986)
|
From page 270... ...
The addition of sputum cytology as a screening technique was considered complementary to chest radiography because 37 cancers were detected by sputum cytology alone. Nearly all cancers detected by cytology were centrally located squamous cell carcinomas.
|
From page 271... ...
Incidence data from the randomized controlled trials showed annual new cancer rates of 4.3 to 6.0 per 1,000 persons. The Hopkins and Memorial studies found similar numbers of cancers in each group (intervention group versus control group in the Hopkins study, 155 versus 162; intervention group versus control group in the Memorial study, 114 versus 121)
|
From page 272... ...
Lessons Learned from Lung Cancer Screening Studies Why was screening with chest radiographs and sputum cytology unsuccessful? Trial investigators and epidemiologists have offered several explanations.
|
From page 273... ...
In addition, the intervention group complied with the 4-month regimen of sputum cytology and chest radiography only 75 percent of the time, thereby reducing the possibility of observing the full impact of the screening. Even under conditions of no contamination, the statistical power of the Mayo study was limited (statistical power refers to the likelihood that a study will find a particular effect if the effect exists)
|
From page 274... ...
argue that overdiagnosis bias is an unlikely problem in lung cancer, given the aggressive course of lung cancer and the rarity of undiagnosed lung cancers found in autopsy studies. The rate of survival among patients with stage I cancers who refused surgery is dismal, suggesting that practically all lung cancers are lethal if left untreated (Sobue et al., 1992a)
|
From page 275... ...
The NCI prevalence data indicate that only 0.39 percent of the screened population had lung cancer. Sputum cytology was a less effective technique since chest radiography detected the majority of cancers.
|
From page 276... ...
A NEW MEDICAL IMAGING SCREENING TEST: THE SPIRAL CT SCAN As a lung cancer screening test, chest radiography lacked the sensitivity to find early-stage cancers. When a cancer is seen on a radiograph it is now common clinical practice to obtain a CT scan to evaluate the lesion.
|
From page 277... ...
During the prevalence screening, spiral CT scans detected 30 lung cancers among 1,000 participants in the ELCAP study for a cancer detection rate of 30 per 1,000 screenings. The cancer detection rate at the Mayo Clinic study was 13.8 per 1,000 screenings.
|
From page 278... ...
278 Cal Cal .= .
|
From page 280... ...
280 Cal Cal ._ · ~ C~ so = so so Cal C~ so ._ ¢ .= U)
|
From page 282... ...
. For the incidence screening years, the ELCAP study once again found the highest lung cancer detection rate, 5.9 cancers per 1,000 screenings compared to 1.4 per 1,000 screenings at the Mayo clinic, 4.1 per 1,000 screenings at Shinshu University, and 2.4 per 1,000 screenings at ALCA.
|
From page 283... ...
The lower survival among lung cancer participants detected during incidence screenings suggests the presence of length bias among the prevalent screening cancers. Implications of Lung Cancer Screening with Spiral CT Scans The results from these uncontrolled trials are promising and leave little doubt that spiral CT is more sensitive in detecting lung cancers than chest radiographs.
|
From page 284... ...
More than half of all participants in the Mayo Clinic Study had indeterminate nodules. This study, which used the most updated screening technology, found a higher rate of lung nodules than in other studies.
|
From page 285... ...
Sputum cytology is considered a good adjunctive screening test since it frequently detects endobronchial cancers, which are usually squamous cell carcinomas. The randomized controlled trials that were started in the 1970s showed that of the four major histologic types of lung cancer, the best prognosis was for squamous cell carcinoma.
|
From page 286... ...
ITS ~ _% T FUTURE DIRECTIONS IN LUNG CANCER SCREENING The promise of new technologies has led to the initiation of randomized controlled trials. Randomized studies of chest radiographs and spiral CT scanning for lung cancer screening are under way (Patz et al., 2000a)
|
From page 287... ...
By improving the sensitivity of scanning, specificity is likely to decline so that false-positive results are likely to increase. The Mayo Clinic used multi-detector technology and found a higher rate of lung nodules than trials using single detector technology.
|
From page 288... ...
Some community physicians routinely perform screening chest radiographs, despite their lack of effectiveness as determined in clinical trials, and despite the lack of endorsement of their use by policy organizations (Black, 1999a)
|
From page 289... ...
SEER Program data show that the incidence rate of lung cancer among those age 65 and older is about 3 to 6 per 1,000 persons per year. Given the relatively low incidence rates, any decision to be screened for lung cancer by spiral CT should be made with full consideration of the rates of true-positive versus false-positive results and the attendant benefits and risks.
|
From page 290... ...
At present, however, randomized controlled trials of screening are ethically sound; the evidence about screening by spiral CT (or other modalities) has not yet been tipped to favor screening.
|
From page 291... ...
The use of chest X-rays for screening appeared to be appropriate at the time and fit with the approach already in use for tuberculosis. Sputum cytology added another screening too!
|
From page 292... ...
In the 1970s four randomized controlled trials on lung cancer screening using chest radiography and sputum cytology were performed. Unfortunately, these randomized controlled trials of lung cancer screening showed no evidence of early detection of lung cancers by these tests (Fontana et al., 1991; Melamed et al., 1984; Tockman, 1986~.
|
From page 293... ...
Findings from uncontrolled trials conducted to date do not provide the level of evidence required to endorse systematic screening with spiral CT scans.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.