Scientists have issued a warning that half of the men who are informed that they have ‘slow-growing’ prostate cancer may be suffering a more aggressive form of the disease.
They have stated that inaccurate testing often understates the potential progress of the cancer. Doctors can only determine the level of treatment once the prostate has been removed by a surgical procedure.
Researchers found that many of the males would undergo surveillance where doctors constantly monitor the symptoms and the tumour before they make the decision on the type of treatment required.
The new findings which have been published in the British Journal of Cancer, suggests that biopsy samples which are taken at the outset could lead to the wrong classification of the cancer.
Dr Greg Shaw, a urological surgeon from the Cancer Research UK Cambridge Institute, has states that their results indicate that the severity of about 50% of male prostate cancers may be under-classified if reliance is placed on pre-surgical tests. He said that this result highlights the urgency for better tests to determine the aggressiveness of the cancer from the start. He said that improving diagnostic tests and biopsy techniques would aid in the accuracy of defining the extent of the cancer.
Dr Shaw said these advanced tests would allow them to counsel patients and be more certain that the cancer which has been identified is suitable for active surveillance or not.
Slow-growing prostate cancer, referred to as ‘pussycats’, are different from aggressive forms, known as ‘tigers.’
In certain cases, depending on the age of the patient when he is diagnosed, it is possible for him to experience a normal lifespan, without threat from the ‘pussycat’ cancer. The more aggressive form of the cancer however, may spread rapidly if it is not destroyed or removed surgically.
Biopsy samples which are examined by microscope are used to rate the aggressiveness of a tumour. Scores are also given to the extent of the spread.
The scientists at Cambridge compared the grading and staging of more than 800 instances before and after surgery to remove the prostate. They discovered that 209 of the 415 patients who had been classified as ‘slow-growing’ and told that it was confined to the prostate had a more aggressive form of the disease. One third, about 131, of the patients had cancers which had spread beyond their prostate gland.
Cancer specialists have said that the methods used to assess prostate cancer severity are the best they have, but as can be seen by these results, it is not always accurate. The Director of Research at Prostate Cancer UK, Dr Iain Frame, stated that accuracy of diagnoses was one of the biggest challenges medical specialists faced.
Image credit: Howard Lake