© 2005 Oxford University Press
IN THIS ISSUE
Efficacy of Community-Based Breast Cancer ScreeningThe efficacy of breast cancer screening in the community may differ from that suggested by the results of randomized trials. Elmore et al. (p. 1035) conducted a matched case–control study among women enrolled in six health plans in five states to examine the efficacy of screening by mammography and/or clinical breast examination among women in two age cohorts (40–49 years and 50–65 years) and in two breast cancer risk levels (average and increased risk). They found small, non–statistically significant associations between breast cancer mortality and receipt of screening during the 3 years prior to the index date for both age groups. The association between screening and mortality was stronger among women at increased risk than among women at average risk, but neither association nor the difference was statistically significant. The authors note that study limitations argue for a cautious interpretation of their findings.
In an editorial, Harris (p. 1021) discusses issues concerning the effectiveness of breast cancer screening for reducing mortality as it is currently practiced within the community. He notes that although the study by Elmore et al. does not resolve the issue of the effectiveness of screening within the community because of its limited power and the relatively low mammography screening rates in all of the groups, it raises several important questions about our current use of screening.
Selective Reporting Biases in Prognostic Factor Studies
Because non-reported and selectively reported information and the use of different definitions may introduce biases in the prognostic factor literature, Kyzas et al. (p. 1043) conducted a meta-analysis of the status of the tumor suppressor protein TP53, a putative prognostic factor for head and neck squamous cell cancer (HNSCC) mortality. They found that the strength of the association between TP53 status and mortality weakened as their analyses moved from 18 studies with published and indexed data to include 13 studies with published but not indexed data and then another 11 studies with unpublished data obtained from investigators. Associations between TP53 status and mortality using the study-specific definitions were even stronger than those using standardized definitions. Selective reporting may spuriously inflate the importance of postulated prognostic factors for various malignancies.
In an editorial, McShane et al. (p. 1023) note the very small number of cancer prognostic markers validated as clinically useful. They emphasize that selective reporting biases are not only a major impediment to meaningful meta-analyses of prognostic marker studies but also have serious implications for interpretation of the entire cancer prognostic literature. They conclude that the tumor marker research community must adhere to sound study design and analysis, much as clinical trialists decided to do decades ago.
HPV Types 16 and 18 and Cervical Precancer and Cancer
Two studies in this issue of the Journal focus on associations between human papillomavirus (HPV) types 16 and 18 and cervical precancer and cancer in women with normal, equivocal, or mildly abnormal cytology. Castle et al. (p. 1066) tested 5060 women in the ASCUS (atypical squamous cells of undetermined significance) LSIL (low-grade squamous intraepithelial lesions) Triage Study (ALTS) for HPV 16 and other oncogenic HPV strains at baseline and followed them for 2 years. The authors found that, of the 542 women who developed cervical intraepithelial neoplasia grade 3 or cancer (CIN3 or greater), the 2-year cumulative risk was 38 times higher for women who were HPV16 positive and seven times higher for women who were positive for other oncogenic HPV types than for women who were HPV negative. Khan et al. (p. 1072) tested 20,810 women who were enrolled in the Kaiser Permanente health plan in Portland, Oregon, for 13 oncogenic HPV strains and followed them for 10 years. At enrollment, 96% of the women had normal cytology, and at the end of the follow-up period, 131 (6%) had CIN3 or greater. The authors found that cumulative rates for CIN3 or greater were 17.2% among HPV16–positive women, 13.6% among HPV18–positive women, 3% among HPV-positive women with one of 11 other oncogenic HPV types, and 0.8% in HPV-negative women. Both groups conclude that identifying women who are HPV16 positive (or HPV18 positive) may be clinically relevant.
Risk of Contralateral Testicular Cancer
Although risk estimates for synchronous and metachronous contralateral testicular cancers vary widely, many clinicians recommend routine biopsy of the contralateral testis for patients diagnosed with unilateral testicular cancer. Fosså et al. (p. 1056) evaluated the risk of contralateral testicular cancer and survival among 29,515 U.S. men diagnosed with testicular cancer before age 55 years. The 15-year cumulative risk of metachronous contralateral testicular cancer was 1.9%. Nonseminoma patients had a 40% lower risk of developing metachronous contralateral testicular cancer than seminoma patients. The 10-year overall survival rate was 93% after a metachronous contralateral testicular cancer diagnosis and 85% after synchronous contralateral testicular cancer. The authors conclude that the low cumulative risk of metachronous contralateral testicular cancer and the favorable overall survival of patients diagnosed with metachronous contralateral testicular cancer do not support routine biopsy of the contralateral testis.
Validity of Medicare Chemotherapy Claims
To determine the accuracy with which data from Medicare claims measure chemotherapy use in elderly Medicare beneficiaries with cancer, Lamont et al. (p. 1080) performed a criterion validation study. They compared goldstandard clinical trial data for 175 cancer patients treated on two clinical trials. They found that the crude sensitivity for chemotherapy administration was 93% and that individual chemotherapy agents had similarly high sensitivities, from 81% for carboplatin to 91% for cyclophosphamide. They concluded that administrative Medicare claims data appear to be a valid source of information for chemotherapy administered to elderly Medicare beneficiaries with cancer.
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