As readers can see from the historical review above, the subject of so-called "colonic adenoma" is really confusing and very controversial. Despite close to a century of investigation and debate, the true nature of colonic adenoma remains a mystery for most, if not all, students of the subject. However, over the years we have gained a lot of understanding regarding the nature of colonic adenoma and a few things can be stated with some certainty. These are: 1. cytomorphologically the cells of colonic adenoma are indistinguishable from those of colonic carcinoma; 2. architecturally it lacks infiltrative growth, a feature often seen in carcinoma; 3. not infrequently it contains focus of, or is associated with, carcinoma; and 4. clinically it behaves like a benign neoplasm in most cases, if not all. Over the years, investigators of the subject were compelled by one or two or all of these findings. Some of them, in particular surgeons, insisted that colonic adenoma was a benign neoplasm because of its benign clinical course. While others, mainly pathologists, impressed by the indistinguishable cytomorphology between colonic adenoma and carcinoma as well as their close association, believed that colonic adenoma is really malignant, obvious at an early stage of development. Caught in between these two opposing views are those who thought colonic adenoma is neither benign nor malignant, so that they invented terms such as premalignant, precancerous, precursor, etc. Although these terms do have some validity, they are not defined and lack specificity and clarity, as Turell stated well in 1964, "The words 'premalignant' or 'precancerous' have been avoided because they are essentially prognostic or statistical terms which indicate only a greater probability of the development of cancer. About the only precancerous aspect of the colon is the colon itself." [8]

So what is the true nature of so-called colonic adenoma? As readers can see, the confusion persists and there is no agreement among investigators of this subject. In Part II of this work, we will continue to review critically contemporary articles of this subject and to see whether this issue has been elucidated.