@denip There were no other factors. All other indicators (CT/PET scan imaging and other blood test levels) look relatively good.... little changed over the past four months. My most recent CA 19.9 level (one week ago) was 273, with previous high of 641 ten months ago and previous low of 43 five months ago. My unusual past circumstance and history of twice changed chemo regimens, as well a couple of other factors, I strongly suspect have impacted the range and trends in my CA 19.9 results. My surgery is now scheduled for April 26 following two more cycles of my current chemo. Wishing the two of you success as well.