Blood transfusions after cancer surgery may hamper patients' survival prospects, according to research from the Netherlands.

Researchers looked at 475 patients who had had surgery for colorectal cancer. They compared the post operation progress of three groups, those being given donated blood; those who were given transfusions of their own blood, which they had earlier donated; and patients who had received no transfusions during their treatment.

They found that patients receiving any type of transfusion, whether of their own blood (autologous) or donated (allogeneic) were at "significantly increased" risk of a recurrence of the disease compared with those not receiving blood.

"The disease free survival was significantly worse in patients in both groups who received transfusions than in the 143 patients who did not, whereas the disease free survival of the patients who received transfusions in both groups did not differ significantly from each other."

Four years after treatment, the survival rate for those having no transfusion was 73 per cent, compared with 59 per cent among those receiving either type of blood.

Of the 136 who had only allogeneic transfusions, 56 per cent survived after four years; of the 102 receiving only autologous blood, 62 per cent; of those receiving a mixture, 66 per cent.

They speculate that those deemed to need transfusions might have been more at risk anyway: "The need for a transfusion could be an indicator of other prognostic factors that are either unknown or difficult to quantify, such as the extent of the tumour and the dissection, the skill of the surgeon, and the nutritional state of the patient."

But they also say that it is possible that transfusions of blood from whatever source "produce the same adverse reactions". They add that the fact of having donated blood itself may be a factor.

"We have found in rats that the donation of blood can decrease natural killer cell activity and stimulate tumour growth. Therefore, the patients in the autologous transfusion group could have had a lower natural killer cell activity than the patients in the allogeneic transfusion group at the time of surgery.

"It seems beneficial to operate on patients with colorectal cancer in such a way that blood transfusions are either avoided or minimized," they conclude.