Dear JACUSTOMER p51h63l8: The only advice I recommend is for you not to be overly worried since the doctors who have examined your child have not found any physical evidence on physical examination and from the history given of any kind of indication that this is cancerous and I think that one of them would have ordered a ultrasound or CT scan if there was anything in their differentials regarding the presentation. If would not hurt for you as parent to request for one of the doctors to order a ultrasound of the left abdominal quadrant(over the spleen) which should include the area under the left rib cage so that you will feel better about the lump in that area, since you feel better now that the gastroenterologist has along with the pediatrician, both diagnosed the other lump on the upper left side of her umbilicus(belly button). At this point of evaluation, no there is no list of cancer symptoms that you should be looking for, unless the doctors evaluating your child discusses with you of findings pointing toward a diagnosis of cancer. It may be best for you to wait until the tests and full or complete diagnostic evaluation on your child is done before becoming overly anxious prematurely.
Discuss with the gastroenterologist again your concerns regarding possibilities of cancer and listen for any further recommendations by this specialist about what workup needs to be done at this time.