Colon and rectal cancer can feel silent until it suddenly is not. A new Finnish study suggests that, for many patients, warning signs may already be visible in specialist records months before the disease is officially diagnosed.
The main clue is not one dramatic symptom, it is a pattern. Nearly three in four patients diagnosed in Finland in 2015 had visited specialized health care during the previous year, and the lead researcher said the findings point to “opportunities to identify cancer earlier.”
The hidden paper trail
Specialized health care means care provided by a specialist or hospital service, not an ordinary check-in for a sore throat. Essentially, this is where people go when a problem has already raised enough concern for more advanced testing or treatment.
The work was led by Elina Hermiö at the Finnish Cancer Registry, with co-authors from Tampere University, the University of Turku, the Finnish Institute for Health and Welfare, and the University of Helsinki.
The team looked at all colon and rectal cancer cases diagnosed in Finland in 2015 and checked specialist visits from the year before diagnosis.
Anemia stood out
One finding jumped off the page. In the blood-related category, anemia was the most frequent diagnosis, appearing among nearly half of patients who had that type of specialist event.
Anemia means the body does not have enough healthy red blood cells to carry oxygen well. That can make a person feel tired, weak, pale, dizzy, or short of breath, the kind of symptoms many people blame on a busy week or bad sleep.
What doctors saw
The common reasons for specialist care included anemia, abdominal pain, benign intestinal tumors, and bowel obstruction. A benign tumor is a growth that is not cancer, but it can still be part of the path that leads doctors to look more closely.
Bowel obstruction is more serious. It means stool or gas is partly or fully blocked from moving through the intestine, a situation that can send someone to urgent care fast–not exactly a subtle warning.
Why early detection matters
Colorectal cancer begins in the colon or rectum, the last parts of the digestive system. It can grow from small abnormal growths called polyps, and some polyps can turn into cancer if they are not removed.
That is why timing matters so much. The National Cancer Institute says some screening tests can find colorectal cancer early and may reduce deaths from the disease, while stool-based tests can look for hidden blood that cannot be seen by eye.
Some cases still appear suddenly
The Finnish results also had a harder message. Nearly one in three patients had no specialist visit recorded in the year before diagnosis, and this was more common among people younger than 65.
Among patients without earlier specialist visits, cancer was more often advanced. Some cases were only found during urgent hospital care, which shows how easily vague symptoms, limited access, or simple bad luck can let the disease move ahead.
Symptoms are easy to miss
Colon and rectal cancer does not always cause symptoms at first. When symptoms do show up, the CDC lists warning signs such as changes in bowel habits, blood in or on the stool, abdominal pain or cramps that do not go away, and unexplained weight loss.
Here is the tricky part: a stomachache after dinner, constipation during a stressful month, or fatigue after work usually has a harmless cause. But when the same issue keeps coming back, or when blood or unexplained weight loss appears, it deserves medical attention.
A signal for health systems
This study is not saying doctors can diagnose cancer from anemia alone. It is saying that repeated patterns in specialist records may help health systems flag patients sooner, especially when several clues appear close together.
A related 2023 Finnish study found that health service use began rising three to four months before diagnosis, and more than half of inpatient episodes started as urgent admissions. That earlier work pointed to possible bottlenecks in access to care and symptom recognition.
What patients can do
For patients, the takeaway is not to panic, it is to pay attention. If a doctor tells you that you have unexplained anemia, or if belly pain and bowel changes keep returning, ask what follow-up makes sense.
Screening remains the bigger safety net for people without symptoms. In the United States, the CDC says most adults should begin colorectal cancer screening soon after turning 45, though people with higher risk may need to start earlier.
The bigger picture
Could some cancers leave clues before anyone knows what they mean? The new research adds a practical idea to the conversation about early detection. The faint footprints may be hiding in test results, referrals, and hospital notes.
For the most part, those footprints only help if someone connects them.
The full study has been published in Acta Oncologica.
