Missed or delayed colorectal cancer diagnosis

The National Cancer Institute says signs of colon cancer include blood in the stool or a change in bowel habits (opens in a new tab), and that they may be caused by colon cancer or by other conditions. A colonoscopy looks inside the rectum and colon. Polyps, which are small pieces of bulging tissue, can be removed and checked under a microscope for signs of cancer (opens in a new tab).

Screening means testing people without symptoms. The U.S. Preventive Services Task Force recommends screening for colorectal cancer in all adults aged 50 to 75 years and in adults aged 45 to 49 years (opens in a new tab). It grades the first A and the second B. The younger group was added on May 18, 2021. Before that the starting age was 50.

The recommendation covers adults 45 years and older who do not have signs or symptoms of colorectal cancer and who are at average risk (opens in a new tab). A person with symptoms is outside it, and a screening schedule does not say what that person needs.

The Task Force says positive results on stool-based screening tests require follow-up with colonoscopy for the screening benefits to be achieved (opens in a new tab). The National Cancer Institute tells patients that after a stool test, a follow-up colonoscopy will be needed if the test is positive (opens in a new tab).

The Task Force’s statement is about what makes screening work, and it sets no deadline for the colonoscopy (opens in a new tab).

These are the Task Force’s and the Institute’s documents, and they are not law. What careful practice required for a particular patient is something a qualified physician has to explain.

In a study of 513 patients diagnosed with colorectal cancer from 1999 to 2007 in one Texas health system, reviewers judged that 161 had at least one missed opportunity to start an examination with a scope. The most common clues were suspected or confirmed iron deficiency anemia, a positive stool blood test and visible blood in the stool (opens in a new tab). Anemia, a blood count finding, had the longest time to referral, a median of 393 days. The study did not measure outcomes.

Colonoscopy has limits too. A 2019 analysis of studies that repeated the examination straight away calculated miss rates of 26% for adenomas and 9% for advanced adenomas (opens in a new tab). An adenoma is a type of polyp that is more likely to become a cancer (opens in a new tab). A cancer found after a colonoscopy that looked clear is not, by that fact alone, proof of a careless examination.

In a 2019 study of malpractice claims over diagnostic errors in primary care, missed cancer diagnoses were 980 (46%) of the cases, most commonly lung, colorectal, prostate or breast cancer (opens in a new tab). Those are shares of lawsuits. They say nothing about how often colorectal cancer is missed among patients.

A 2017 study followed patients in one health system after a positive stool test. Against colonoscopy at 8 to 30 days, it found no significant differences in risk for follow-up at 2 months, 3 months, 4 to 6 months or 7 to 9 months (opens in a new tab).

At 10 to 12 months the risks were significantly higher (opens in a new tab), with odds ratios of 1.48 for any colorectal cancer and 1.97 for advanced-stage disease. Beyond 12 months they were 2.25 and 3.22. That is an association, and the study did not measure survival.

Studies of patients under 50 cut against a simple story. In a 2017 study, younger patients had a significantly longer median time to diagnosis, 128 days against 79 (opens in a new tab), yet the authors concluded that their more advanced stage could not be explained simply by delay. A 2016 study of rectal cancer reported that the delay in diagnosis did not adversely affect stage at presentation or 5-year survival (opens in a new tab). Each comes from a single medical center, and neither shows that delay is harmless.

These figures describe groups of patients. None says what a delay meant for one person. In Illinois a patient has to prove that the care was negligent and that the negligence more probably than not caused the harm, which can be a lost chance of a better outcome. That takes expert proof in each case.

Three records matter: the first result, such as a blood count or stool test, the colonoscopy report, and the pathology report on anything removed.

Federal rules require a laboratory to keep pathology reports and tissue slides for at least 10 years (opens in a new tab), and other test reports for at least 2 years. A hospital licensed under the Illinois Hospital Licensing Act must preserve its medical records for not less than 10 years (opens in a new tab). That Act does not cover hospitals run by the federal government or by a state university (opens in a new tab).

Illinois law requires a health care facility to let a patient examine the records of their care and have copies made (opens in a new tab). It helps to write down the dates of your visits and tests, and what you were told.