Inclusion Criteria:  Age > 18 years old AND Were treated with curative intent AND Are planning to undergo regular follow-up and monitoring for cancer recurrence per standard of care at the enrolling site AND Provided written informed consent to participate in the study AND Are willing to have de-identified clinical data shared with investigators at regular intervals as outlined in the study protocol and informed consent AND Are willing to provide blood samples at enrollment and at subsequent clinical visits coinciding with standard of care follow-up, for up to 5 years as outlined in the study protocol and informed consent AND Have at least one blood sample collected 4-12 weeks after completion of primary treatment of the Index Cancer Have a histologically confirmed Index Cancer that qualifies for inclusion, defined as:  Primary Study Cohorts  Cohort 1: Muscle invasive carcinoma of the bladder, ureter, or renal pelvis (stage II-III), Cohort 2: Non-small cell lung cancer (stage II-III), Cohort 3: Invasive breast carcinoma with all of the following:  Clinical stage T1-4/N0-3/M0 at presentation AND Completed preoperative systemic chemotherapy-containing regimen AND Underwent definitive surgical resection of the primary tumor AND Has pathological evidence of residual invasive carcinoma in the breast and/or axillary lymph nodes AND Hormone receptor and HER2 status are known  Exploratory Cohorts  Cohort 4: Stage IIb-III cutaneous melanoma or limited (resectable) stage IV melanoma treated with curative intent, Cohort 5: Esophageal or gastroesophageal junction carcinoma (stage II-III), Cohort 6: Gastric adenocarcinoma (stage II-III), Cohort 7: Surgically resected pancreatic adenocarcinoma, Cohort 8: Invasive squamous cell carcinoma of the head and neck (includes stage I-III oral cavity, oropharynx, hypopharynx, larynx, nasopharynx, nasal cavity, paranasal sinus, and salivary gland cancers), Cohort 9: High-risk epithelial ovarian or Fallopian tube carcinoma (defined as stage IC-III or stage I that has high grade (grade 3-4) or clear cell histology), Cohort 10: High-risk endometrial carcinoma (defined as having any of the following: serous or clear cell adenocarcinoma histology (any stage), grade 3 or 4 deeply invasive (T1b or greater) endometrioid carcinoma, stage III disease (any histology)), Cohort 11: High-risk renal cell carcinoma (defined as high grade (grade 3-4) stage II, stage III or limited (resectable) stage IV treated with curative intent)  Exclusion Criteria:  History of allogeneic organ or tissue transplant Index cancer has neuroendocrine histology History of another primary cancer, with the exception of the following (if adequately treated and the patient is without evidence of disease at the time of enrollment): in situ cancers, non-melanoma skin carcinoma, localized low-risk prostate cancer (Gleason score < 6) with PSA in the normal range, and stage I papillary thyroid carcinoma. Known distant metastasis at time of enrollment (with the exception of participants with limited/resectable stage IV cutaneous melanoma or RCC) Is participating in a clinical trial or another observational study that is evaluating the performance of another genomic test in the post-treatment surveillance setting at predicting/detecting recurrence