Which types of cancer are less noticeable?

Varies. Some cancers are not detected until widespread and it is too late to intervene. The real question is why? Some may not present with early symptoms because of their "silent" location. For example, pancreatic cancer off of the tail of the pancreas grows, spreads and seeds the abdomen with minimal symptoms. Some cancers of the GI tract are found on screening tests.When symptomatic, it is too late.