This can lead to symptoms such as fatigue, weakness, dizziness, and skipped or rapid heartbeats.
As the tumor gets larger, the bleeding and blood loss worsen.
On top of this, chronicinflammationcaused by the tumor alters how the body uses iron.

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In those who get chemotherapy or radiation, around 67% can expect to have anemia.
With that said, iron-deficiency anemia can also be due to slow, chronic internal bleeding.
2017;32(11):1617-24. doi:10.1038/s41598-018-19572-y
American Society of Hematology.Anemia.
2016; 38(4): 325330. doi:10.1016/j.bjhh.2016.05.009