The quest for reliable biomarkers to identify new and recurrent cancer

rightly point out that currently approved biomarkers have focused on the assessment of single proteins, even though no single biomarker has demonstrated sufficient sensitivity and reproducibility for clinical use in the diagnosis of breast cancer among individuals presumed to be healthy and disease free. Approved biomarkers for the diagnosis of recurrent breast cancer perform rather poorly and are not in routine use in most large centers. The authors cite investigations with autoantibodies and DNA methylation as holding particular promise in biomarker development for the diagnosis of new and recurrent breast cancer. For many years, prostate-specific antigen (PSA) was considered one of the best diagnostic cancer markers, and was part of clinical practice. However, the lack of specificity of PSA as a marker for prostate cancer, combined with the relatively benign nature of prostate cancer progression in many men who develop the disease has led clinicians to question its continued use. Because national bodies such as the US Preventive Services Task Force now recommend against PSA screening for prostate cancer, the research community has searched for other noninvasive markers such as proteins, circulating tumor cells and nucleic acids in the blood or urine of patients with prostate cancer. As Sardana and Diamandis point out, these markers, in combination with PSA, are being evaluated to develop a multiple-biomarker approach to the diagnosis of new and recurrent prostate cancer [2]. Adenocarcinoma of the pancreas (pancreatic cancer) is generally lethal. The reasons for this are many, but certainly one of the most important is late diagnosis. Survival is rare in the absence of early diagnosis, yet >50% of individuals with very small lesions confined to the pancreas are alive 5 years after diagnosis. Indeed, as Batra et al. point out, pancreatic cancers on average have a relatively long time There has been measurable progress in personalizing the treatment of adult malignancies. Once the diagnosis of cancer is made and the tumor is available, it can be genotyped and phenotyped to optimize the intervention that will be administered. Moreover, large-scale assessment of tumors has allowed the development of targeted therapies based on the mutations that drive tumor progression. Far less progress has been made in the development of biomarkers for the diagnosis of new or recurrent cancer. Perhaps this is not surprising, given the multitude of mutational and epigenetic events that can occur during cancer development and progression. In this issue of Biomarkers in Medicine, we review the state of the science in biomarker development for breast, ovarian, prostate and pancreatic cancer. Tang and Gui review the current state of breast cancer biomarker research, and future directions [1]. They present four principal areas of promise from biomarker development� combining new with established markers to optimize cancer diagnosis; using biomarkers for the early determination of treatment response and disease recurrence/survival; guiding therapy; and facilitating the identification of the most promising drug candidates for therapeutics worthy of further development. The articles in this themed issue focus on the first and second areas� the diagnosis of new and recurrent cancer. The authors review several serum and tissue markers that have been identified as clinically useful in the management of patients with breast cancer. One major advantage of biomarker research for individuals with cancer is the presence of tumor tissue for analysis, which is not present in individuals without such a diagnosis. Tissue sampling in the absence of a suspicion of cancer is difficult to justify. For this reason, body fluid analysis holds greater promise in biomarker development for individuals without the presence of a lesion that requires biopsy. The authors Foreword