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FOBT Colorectal cancer screening is effective only in males


Examination of Colorectal Cancer (CRC) with occult blood feces (FOBT) improves results in moreso men than in women and especially in men with tumors on the left, say Finnish researchers. Their conclusion stems from a reanalysis of the data from an extensive screening study.

The Finnish screening program FOBT (2004-2011) was conducted in over 320,000 men and women aged 60-69 years. The participants were randomly assigned to control and control arms. The results of this study, published in 2015, found no difference in CRC mortality between the two arms, in contrast to findings from several previously randomized clinical trials.

Now, a team of researchers, led by Laura Koskenvuo, MD, PhD, a gastrointestinal surgeon at the University Hospital in Helsinki, Finland, re-examined the data to evaluate the results "beyond mortality."

They found that FOBT biennial screening "appears to be effective in improving more different outcomes in men, but not in women."

It was particularly beneficial in men with tumors on the left. In this subgroup, FOBT screening was associated with better overall survival, with lower rates of nonradical resection, and a reduced need for postoperative chemotherapy.

However, these benefits were not seen in women, or in men or women with straight tumors.

The research was published online on November 21 in British Journal of Surgery.

The team suggests that given that FOBT screening does not seem to be associated with improved survival in women, screening by different methods or at different intervals or age should be considered in women.

Details about the findings

The completed FOBT study covered about 41% of Finnish men and women who were in the target age group (60-69 years) by the end of 2011.

Although there was no significant difference in CRC mortality between the control arm and the control arm, the results suggested that there was a reduction in CRC-associated mortality with men's screening and increase among women. Such a finding was also observed in other studies of biennial FOBT, the researchers say.

Basically, it has not been found that cancer screening has an impact on global mortality, "Koskenvuo commented in a press statement.

However, they can still be useful in other ways. "We wanted to study whether patients could avoid more intense treatments if they participated in screening for colorectal cancer," she explained.

Therefore, the team collected data on CRC diagnosis from the Finnish Cancer Registry and examined patients' medical records to identify the clinical and pathological TNM status; symptoms and extent of surgery; the need for patients to perform emergency surgery, stomach or chemotherapy; and histopathological diagnostics.

Of the 321,311 people in the study, 743 CRC cases were detected in the screening arm, and 617 were detected in the control arm.

Patients in the screening group were more likely to be successful at eliminating the entire tumor, less likely to require chemotherapy, and less likely to undergo emergency surgery.

The control group had 50% more emergency surgeries, 40% more incomplete tumor removal and 20% more chemotherapy treatments than patients in the screening group, explained co-author Ville Sallinen, MD, PhD, a deputy professor at the University in Helsinki.

CRC was less common in women than in men at a rate of 0.34% versus 0.50% (risk ratio [RR], 0.82).

Women were less likely to be asymptomatic than men, at 16.7% versus 22.0 (RR, 0.76). Abdominal pain was the only symptom that was significantly more prevalent in women than in men (RR, 1.36).

Women were much more likely to have tumors on the right than men, at 32.0% versus 21.3% (RR, 1.51).

The cancer in patients in the screening arm was lower than T (RR, 1.25), N (RR, 1.14), and M (RR, 1.33) compared to control arm cancers.

In men with left tumors in patients in the screening arm, the cancer cases were of the inferior category N (RR, 1.23) and the M (RR, 1.57) category than in the patients in the control arm.

In the case of men with tumors on the left, those in the control arm were more likely to undergo non-radicular resections than those in the screening arm, at 26.2% vs. 15.7% (RR, 1.67) and were more likely to receive postoperative chemotherapy at 61.6% versus 48.2% or (RR, 1.28).

Survival was more severe in the control arm than in the screening arm in men with CRC [HR], 1.31), but was not different in women [HR, 1.07].

Among men, the overall survival rate at 5 years was 68.8% in the screening arm, compared to 61.5% in the control arm. Among women, rates were 70.7% and 71.5% respectively.

In terms of tumor appearance, in men with tumors on the left side, survival was better in the selection arm than in the control arm (HR, 1.37).

This survival benefit was not seen in men with tumors on the right, however (HR, 1.19)

. Survival rates were not affected by the tumor appearance in women.

Co-author Nea Malila, PhD, Director of the Finnish Cancer Registry, Helsinki, said the size of the large sample is a force of the study.

"She randomized an enormous number of people into the public health system, which meant we could objectively assess the benefits of screening," she observed.

"Similar studies were not available elsewhere," she said.

"In the future, we need to examine whether different screening techniques could improve the situation of female patients and facilitate the diagnosis of colorectal cancer on the right side," the researchers conclude.

The study was supported financially by Vatsatautien Tutkimussäätiö, research funds at the University Hospital in Helsinki, the Mary Foundation and Georg Ehrnrooth, and the Cancer Finland Foundation. The authors did not disclose any relevant financial relationship.

Br J Surg. Published online November 21, 2018. Full text

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