I understand that if it is caught early enough, cancer can be fully removed never to see it come back again. Usually though, it has already spread too far and diffuse or it might be in a spot that cannot be easily removed. So, I am curious to know actual numbers. What percentage of patients with cancerous tumours have successfully had them completely extracted?
Surgery is typically an option taken with either superficial cancers, ones that do not tend to metastasize, ones that create well concentrated tumors, and/or are not next to crucial structures. The surgeon typically removes the tumor and some surrounding healthy tissue to ensure complete removal(1). In reality any tumor could be potentially operable if we had perfect hands, but a tumor is deemed inoperable when the surgeon himself does not feel safe attempting to excise it(2).
Typically survival rates from cancers depend on the stage they were caught in (3). Early cancers can usually be successfully treated with chemo and/or surgery, although it should be noted even if surgery is successful it is generally used along with chemo regardless just as an extra precaution(4).
In all honestly it is difficult to answer your question with percentages or raw numbers. It depends wildly on the type of cancer, tumor progression, location of the tumor, and unfortunately the skill of the surgeon himself/herself.
Further complicating those numbers is the fact that not all surgeries are intended for complete removal. Sometimes you may want a diagnostic sample or to perform a palliative surgery, in which you remove enough of the tumor to relieve symptoms for a patient that is usually beyond any other means of help(4).
More than likely you'll find much more reliable numbers in the other types of cancer therapies, most specifically in targeted biological/genetic approaches which are becoming more and more prevalent. Many of these are hopeful but for now far from human clinical trials (5,6).
A brand new finding, that is in clinicals from what I understand, is called SR2943 which targets the famed "Warburg Effect" of cancer cells. However even this has variable effects depending on the type of cancers since they do not all use this effect to the same degree, maybe some do not use it at all(7).
There is even some evidence to suggest cancer cells use amino acids at an abnormal rate and perhaps we should do something similar, that SR2943 does to limit lipogensis, but specifically for amino acids(8).
Hope this helps. I decided to go a bit beyond your question as I felt it may help you to understand the concept of cancer and tumors a bit more.