However, development of methods for noninvasive detection of early-stage tumors has remained a challenge. The test detected stage 1 or 2 colon, breast, lung or ovarian cancers between 59 percent and 71 percent of the time when assessing 200 patients previously diagnosed with cancer, researchers found. However, these approaches have largely been applied in patients with late-stage cancers or have used tumor tissue sequencing to guide mutational analyses in the blood. More than 14 million individuals are newly diagnosed with cancer worldwide each year, with the majority having invasive or metastatic disease ( 1 ). "Finding any marker in a stage 1 ovarian cancer patient is very important, because this is a tumor that usually presents at a much later stage," Lichtenfeld said. No false positives were detected over the 80,930 bases analyzed in 38 dilution analyses, resulting in less than one error in 3 million bases sequenced (error rate of <3.3 × 10−7 false-positive mutation calls per base; specificity, >99.9999%; table S2). These individuals were not known to have cancer and provided their blood samples as part of a routine cancer screening visit (colonoscopy or Papanicolaou test). More than three quarters of patients with advanced disease (stages III and IV) and 62% of patients with localized disease (stages I and II) were detected among all tumor types (Table 2). For the study, the team screened blood samples from patients with breast, lung, ovarian and colorectal cancers, looking for 58 genes typically linked with these cancers. Comparison of mutations in plasma with those in matched tumor and blood cells Of the 194 patients in our study, 152 cases had matched tumor and normal tissues that we analyzed using an independent targeted NGS approach (tables S3 and S4). They also sequenced mutations in tumors from 100 of the patients studied, and found that in 82 patients, the same mutations found in the blood corresponded with those found in the tumor tissue.
– Human blood is rich with genetic material, and scientists have in recent years taken many steps forward in decoding it. The latest announcement—that a blood test can spot cancer at its earliest stages—has the potential to save millions of lives as treatment is administered earlier in the disease's progression, reports Reuters. Reporting in the journal Science Translational Medicine, scientists say that by analyzing DNA fragments in blood to look for several dozen cancer-driver genes, they spotted 86 out of 138 stage 1 and stage 2 cancers; they also confirmed no trace of cancer in 44 healthy patients (in other words, there were zero false positives). Some call this minimally invasive test a "liquid biopsy." "This is one of the first studies that has looked directly at early-stage cancers," says lead author Dr. Victor Velculescu, an oncologist at Johns Hopkins Kimmel Cancer Center. While the test is proof-of-concept and not yet ready for prime time, detecting 62% of cancers that were only in stages 1 or 2 is a major milestone, experts say. For instance, less than one in five ovarian cancers are caught that early, when the survival rate is higher than 90%; those that are caught after the cancer has spread face a dramatically lower 40% survival rate five years out, per HealthDay News. For this study, however, the blood test caught early-stage ovarian cancer 68% of the time. Scientists hope they can get the test much closer to a 100% detection rate. (This cancer treatment is being hailed as the most exciting in a lifetime.)