My dad devastatingly passed away last week following a 10 month battle with metastatic lung cancer. I’ve since come to learn about errors in his treatment that may have given him more time and potentially stopped the cancer spreading as much as it did in a short space of time. His cancer was never curable but we were told he would have ‘years of treatment, not weeks/months’. 
Being on the correct treatment from the beginning would have prevented him from having multiple hospital admissions with illnesses related to the treatment she should not have been given. The oncologist told me that the initial oncologist had missed the type of cancer he had through what he thinks may be an admin error. I couldn’t believe what I was hearing!
The last few weeks that we learned his cancer was kicking off again, we waited 6 weeks due to various obstacles/mess up’s for results of biopsies and he died within the time scale. This shouldn’t have taken anymore than 2-3 weeks. 
I can’t help but feel anger that my dad should still be here and he was let down by the very people we trusted had the expertise to give him to best treatment he could that would prolong his life. 
I also feel guilt, sadness, frustration. How can this happen?