With National Colorectal Cancer Awareness Month coming to a close, doctors are reminding Americans that timely screenings save lives -- especially during the pandemic.

The early days of the COVID-19 pandemic were marked by society shutting down, which included doctors' offices nationwide. For elective procedures, a delay meant a nuisance, but not a dangerous one. For colorectal cancer screenings, however, delays can lead to more significant implications.

Colorectal cancer is an umbrella term for cancers of the large intestine -- the colon and the rectum. It is both the third-most commonly diagnosed cancer as well as the third-most deadly.

As the pandemic unfolded, colorectal cancer specialists watched with concern, knowing an untold number of patients were missing opportunities to catch cancer early enough to treat.

"If people aren't getting their screening, we know that a certain percentage of people are going to go on to develop a cancer that otherwise could have been picked up," said Dr. Michael McGee, a gastrointestinal surgeon at Northwestern Memorial Hospital.

National data corroborated a domino effect from delays in screening to delays in diagnosis. By spring 2020, the number of clinic visits to discuss new diagnoses of colorectal cancer was less than half than in the year prior. As researchers predicted, an apparent drop in colorectal cancer diagnoses did not signal that the cancers were not there, but rather that they were not being found -- or sought out.

Now that clinics are fully open with proper COVID-19 safety protocols in place, the delays have caught up with patients. Dr. Aparna Kalyan, an oncologist focused on gastrointestinal cancers at Northwestern Memorial Hospital, is seeing more patients with late-stage disease than she had pre-pandemic.

"It's hard, because you don't want to put the guilt factor on patients," Kalyan said. "So you sort of have to say, well, this happened, now we have to talk about the treatment part of it."

The results of delayed screening and diagnosis will continue to come to light, researchers say. One estimate predicted thousands of excess deaths from colorectal cancer, an effect that may continue for the next several years.

Experts warn that delays in screening go beyond the effects of the pandemic, touching the lives of many minority groups and a troubling number of young people with colorectal cancer.

Over the last decade, while cases of colorectal cancer have decreased in adults over 55 -- thanks in large part to cancer screening -- rates in people younger than 55 are increasing. The late 2020 death of 43-year-old actor Chadwick Boseman drew attention to this alarming trend that experts still can't explain.

"A lot of times, young people especially don't think of it," Kalyan said. "But that does have implications."

Similar implications lead to colorectal cancer affecting low-income and minority patients more severely. The reasons are twofold: There's a disparity in access to screening, which leads to diagnosis late in the course of the disease, and a lack of access to timely treatment, which leads to higher death rates.

"Many low-income and minority patients do not have insurance or regular health care providers," said Dr. Fola May, a gastroenterologist, quality director and health equity researcher at UCLA Health. "In these cases it is very unlikely that an individual knows about the importance of screening or is able to obtain a screening test."

May cited evidence that, compared to white Americans, Black Americans are 40% more likely to die from the disease. It is a number that, outside of a pandemic, is sobering, but in the midst of a year that has disproportionately affected minority communities, is alarming.

The path forward, experts say, is to continue raising awareness about the disease and screening those who qualify.

The best test for colon cancer is a colonoscopy, a procedure in which a small camera is used to inspect the inside of the large intestine and small-scale tools can directly remove concerning areas. Another common way to screen is by collecting an at-home stool sample that can be tested for the genetic signature employed by cancer.

For most people, screenings should begin around age 45 to 50, but clinicians stress that people with a family history of colorectal cancer, or worrisome symptoms, should talk to their doctors about being screened sooner. Doctors should check in with their patients who are due for screening -- especially those at risk for worse outcomes -- to ensure that it is done.

"The combination of low screening rates and poor access to timely treatment contribute to the disparities in death from colorectal cancer," said May. "We need to do a better job at providing information about how common colorectal cancer is and how important screening can be to prevent disease."

Eric Silberman, MD, a resident physician in internal medicine at Northwestern Memorial Hospital, is a contributor to the ABC News Medical Unit.

Mishal Reja, MD, a board-certified internal medicine physician and a contributor to the ABC News Medical Unit, contributed reporting.