Air carrier Flight Attendant reported there was a passenger who may have had biohazardous medication as carry-on baggage but the reporter is also unsure if that was the case as the baggage had passed security.

Narrative

I saw two women approaching the doorway from the jet bridge. The one woman reminded the other woman to zip the extension portion of her very wide hard sided standard sized roll-aboard bag in order to reduce its width. While zipping; the 2nd woman checked her own similar sized bag and was seated. The woman who had zipped the bag was reluctant to give her bag to the Ramp Worker waiting to receive it for cargo. Instead she approached (and thus blocked) the boarding door; (a scene played out multiple times per flight and is both repetitive and wearying.) She insisted that the bag come onboard but it was in no way going to fit in any of the approved locations even spanning the width of both underseat stowage spaces; should I have re-seated her to open seats on the other side. I assured her it was very safe; especially debating a hub and arriving at an outstation. She said her medications were in there; to which my standard response is to remove those and bring them onboard; but leave the bag. At this time she said that almost her entire bag was medications. At this point; I could tell that there was some cognitive dysfunction of some sort and giving the benefit of the doubt; I thought it might've been a form of dementia. So I offered a Flight Attendant (FA) gray bag and I offered for her to place her medications into the gray bag and that that could go under the seat in front of her; but this was her only remaining option; because her hard sided suitcase was simply too large for the storage on our plane. At one point; she explained that she was feeling fatigued because she had suffered a brain aneurysm; and at that point; it was more important to me to lessen her anxiety.Her medications filled a gray bag. She was one of my frequent flyers traveling alone; (the woman who was assisting her had befriended her at the gate compassionately; similar to the way that I was dealing with her compassionately; but she was not an official travel companion of any kind.) The next closest pass was a gentleman and another gentleman in the rows behind; for the front of the aircraft was emptied to accommodate more weight in the back; on the passenger manifest; and will be important upon the following fact. The woman was being very chatty. I'm assuming because of the stress and the cognitive issues; and as I was helping her to situate her bag for maximum legroom; she told me that her chemotherapy medication had been specially packed by her husband who was a doctor in a suitcase; which was foil lined. The medication was in perhaps seven black makeup bags. I have no experience with cancer treatment as my only relative with cancer selected not to have treatment. With my own reasoning; I was able to quickly think to myself that chemotherapy medication is not radiation; and it must not be liquid because it wouldn't have gotten through security. I did not see any markings on any of the black cloth bags or the suitcase such as were in my FA manual indicating hazardous materials.When I saw that her bag had come out from under the seat again; I offered to lean down and re-situate the bag for more comfort for her; which is a way that I get most people to push their bags further under the seat without giving them another order. I tell them that I'm trying to get them a little more legroom and get them a little bit more comfort; and would they mind if I helped them to situate their bag for under the seat in front of them. It was at this time she told me that I should not be exposed to her medication; and that she wished she could've kept it in her bag that was especially foil lined by her husband; the doctor. That it was her chemotherapy medicine that she administers herself because she herself was a certified nurse practitioner and contracted a brain tumor when she was pursuing her medical doctor's degree... and then I was beginning to realize that I was dealing with someone with high intellect; yet some cognitive dysfunction. It was at this time that I informed the Captain of all that had been conveyed to me about chemotherapy medicines. And I asked him; Are you comfortable with this?" He said yes; and we closed on time and operated the flight.During cruise again the passenger was very chatty so I decided to bank any of the information that she gave me; and it was not awkward for me to ask how this medication could adversely impact me if I were exposed to it. Her response was that the medicine should not be near anyone who was pregnant for example; to which nobody nearby was still of child; bearing age or capability; including myself. I asked her if we would need to decontaminate her seat after she had deplaned and before another person was to sit there; because I was considering blocking off that seat and possibly the seat before and behind; given the further information that I was getting. At the end of the flight the woman hugged me because she said that I had good plane side manner; so there was no bad report and if she had never said; the medicine was something that I should not be exposed to; it would've been a win as far as customer service and for one of our frequent flyer special passengers. However; I felt it necessary to run all this information past the Captain. The Captain had some limited experience with chemotherapy and said that the only safety precautions he [and] his wife took when handling parent's chemotherapy drugs was to wear gloves. However; we both determined that it might be a good idea to fill out a cabin safety report regarding the situation; in the event that there had been a breach in screening; or policy. And then we continued with operating another four flights afterward.Cause: Passenger concern; anxiety; perseveration; and cognitive impairment affecting the ability to understand that her bag would be immediately placed into the cargo hold in ZZZ and immediately returned planeside at ZZZ1. If the items were liquid medicines; and were permitted by the TSA; yet were some form of a biohazard; then I would have to question what is happening in the ZZZ security checkpoint. And if necessary; provide education to whatever agent would have left a biohazard through. None of us are pharmacists; oncologists; or experts.Suggestion: It is tough for me to think of a suggestion; because I want to believe that nothing gets past the security checkpoint that should not be on board the aircraft. But also; foil lined or not should those materials been up in the cabin in her previous connecting flights? I would hate for a customer who is already most likely close to the end of her life or struggling with health to be banned from flying. I am not a pharmacist or an oncologist so I really can offer no suggestion. Only more questions and those questions would need to be answered by an expert."