Colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States.1 In 2022, there were an estimated 151,030 new CRC cases and 52,580 deaths.1 Options for CRC screening of patients at average risk include stool tests (annual fecal immunochemical test [FIT], annual guaiac-based fecal occult blood test, or stool FIT-DNA test every 1 to 3 years), colonoscopies every 10 years, flexible sigmoidoscopies every 5 years (or every 10 years with annual FIT), and computed tomography (CT) colonography every 5 years.2 Many health care systems use annual FIT for patients at average risk. Compared with guaiac-based fecal occult blood testing, FIT does not require dietary or medication modifications and yields greater sensitivity and patient participation.3
The COVID-19 pandemic and staffing issues have caused a scheduling backlog for screening, diagnostic, and surveillance endoscopies at some medical centers. As a result, FIT has become the primary means of CRC screening at these institutions. FIT kits for home use are typically distributed to eligible patients at an office visit or by mail, and patients are then instructed to mail the kits back to the laboratory. For the test to be as sensitive as possible, FIT kit manufacturers advise laboratory analysis within 14 to 15 days of collection, if stored at ambient temperature, and to reject the sample if it does not meet testing criteria for stability. Delayed FIT sample analysis has been associated with higher false-negative rates because of hemoglobin degradation.4 FIT sample exposure to high ambient temperatures also has been linked to decreased sensitivity for detecting CRC.5
US Postal Service (USPS) mail delivery delays have plagued many areas of the country. A variety of factors, including the COVID-19 pandemic, understaffing, changes in USPS policies, closure of post offices, and changes in mail delivery standards, may also be contributory causes. According to the USPS website, delivery standard for first-class mail is 1 to 5 days, but this is not guaranteed.6
The Jesse Brown Veterans Affairs Medical Center (JBVAMC) laboratory in Chicago has reported receiving FIT kit envelopes in batches by the USPS, with some prepaid first-class business reply envelopes delivered up to 60 days after the time of sample collection. Polymedco, a company that assists US Department of Veterans Affairs (VA) medical centers with logistics of FIT programs for CRC screening, reports that USPS batching of FIT kits leading to delayed delivery has been a periodic problem for medical centers around the country. Polymedco staff remind USPS staff about 4 points when they encounter this issue: Mailers are first-class mail; mailers contain a human biologic specimen that has limited viability; the biological sample used for detecting cancer is time sensitive; and delays in delivery by holding/batching kits could impact morbidity and mortality. Reviewing these key points with local USPS staff usually helps, however, batching and delayed delivery of the FIT kits can sometimes recur with USPS staffing turnover.
Tracking and identifying when a patient receives the FIT kit is difficult. Patients are instructed to write the date of collection on the kit, so the receiving laboratory knows whether the sample can be reliably analyzed. When patients are notified about delayed delivery of their sample, a staff member asks if they postponed dropping the kit in the mail. Most patients report mailing the sample within 1 to 2 days of collection. Tracking and dating each step of FIT kit events is not feasible with a mass mailing campaign. In our experience, most patients write the date of collection on the kit. If a collection date is not provided, the laboratory will call the patient to confirm a date. Cheng and colleagues reviewed the causes for FIT specimen rejection in a laboratory analyzing specimens for VA patients and found that 14% of submitted samples were rejected because the specimen was received > 14 days after collection, and 6% because the patient did not record the collection date. With a series of interventions aimed at reminding patients and improving laboratory procedures, rates of rejection for these 2 causes were reduced to < 4%.7 USPS delays were not identified as a factor or tracked in this study.
It is unclear why the USPS sometimes holds FIT kits at their facilities and then delivers large bins of them at the same time. Because FIT kits should be analyzed within 14 to 15 days of sample collection to assure reliable results, mail delivery delays can result in increased sample rejection. Based on the JBVAMC experience, up to 30% of submitted samples might need to be discarded when batched delivery takes place. In these cases, patients need to be contacted, informed of the problem, and asked to submit new kits. Understandably, patients are reluctant to repeat this type of testing, and we are concerned this could lead to reduced rates of CRC screening in affected communities.
As an alternative to discarding delayed samples, laboratories could report the results of delayed FIT kits with an added comment that “negative test results may be less reliable due to delayed processing,” but this approach would raise quality and medicolegal concerns. Clinicians have reached out to local USPS supervisory personnel with mixed results. Sometimes batching and delayed deliveries stop for a few months, only to resume without warning. Dropping off the sample directly at the laboratory is not a realistic option for most patients. Some patients can be convinced to submit another sample, some elect to switch to other CRC screening strategies, while others, unfortunately, decline further screening efforts.
