After the first booster, they checked her tumor marker after 1.5 months. She had the blood test and it was 55-57 . That is good; After the first booster, they checked her tumor marker after 1.5 months. She had the blood test and it was 55-57 . That is good; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP), Program ID: The reporter is the patient.  A 62-year-old female patient received BNT162b2 (BNT162B2), as dose 3 (booster), single (Batch/Lot number: unknown) for covid-19 immunization; palbociclib (IBRANCE). The patient's relevant medical history was not reported. Concomitant medication(s) included: LETROZOLE. Vaccination history included: Bnt162b2 (Dose 1, Single), for Covid-19 Immunization; Bnt162b2 (Dose 2, Single), for Covid-19 Immunization. The following information was reported: TUMOUR MARKER DECREASED (non-serious), THERAPEUTIC RESPONSE UNEXPECTED (non-serious), outcome "unknown" and all described as "After the first booster, they checked her tumor marker after 1.5 months. She had the blood test and it was 55-57 . That is good". Relevant laboratory tests and procedures are available in the appropriate section. The action taken for palbociclib was unknown.  Additional Information-Additional Information: The patient was calling about medication. She has reported side effects from medication, and the COVID vaccine affected her side effects. She was hard to understand. She has spoke with this department before. She now has further information to provide. She usually had treatment with medication and letrozole. She got them together through insurance approval. She took medication, and she must took Letrozole. She has been on this treatment for years. She wanted to share how she benefitted from the Pfizer COVID vaccine. What she experienced. It would be good for Pfizer as a company to know to try help more people. She has been going through this since last year. At first she was at least 2-5, and severe. She decided to stop Letrozole, and only take medication during the vaccine. The government wanted everyone to have the vaccine. She was surprised it was working. After getting her first COVID vaccine, her tumor marker dropped very low, and it stayed that way and kept working until January. Her chemo marker was higher / higher than normal before. The first two shots last 7 months. She stopped the letrozole. After 7 months she got the most benefit from the COVID shot. Once the vaccine expired in her body, she went to get the COVID vaccine. She knew later on she would have the booster, and she was not really worried about Omicron.  She could tell she benefitted from the COVID vaccine. Every two months she could tell by her tumor markers that it was working. Her tumor markers were lower than before normal treatment.  She was so happy. When she was originally taking the Letrozole, Ibrance and the COVID vaccines, the side effects she normally had were stronger. That was why she quit the Letrozole.  After the COVID vaccine- 2 shots, she had swollen knees, she couldn't walk, her ankle was swollen. She had fatigue and muscle ache. All the common side effects of COVID vaccines. She had nausea but it was minor. But all of those side effects she had from the cancer medicine. After the COVID shots those side effects worsened.  She decided on her to stop letrozole which was an estrogen blocker. There was not just side effects or Something about the two medications with the vaccines together were too strong. Seven months after the COVID vaccine, her tumor marker did climb up to 18-20. Now it is 40-55. After the first booster, they checked her tumor marker after 1.5 months. She had the blood test and it was 55-57 . That was good. So with another booster it will drop. The government will not allow her to get another booster for certain amount of months. She was taking the medicine already before the vaccine. The booster showed it was working again. Her tumor marker should be 55-70 something or 30-55 something . It has been staying at 55-57 since the booster. With another booster, it may drop as much as it did a year ago.  They are still monitoring her . She cannot wait to take the next booster to prove it is working .  She wanted to report to Pfizer because she knows they are monitoring  this. She knew she was on an estrogen blocker , so for the booster she had to make a decision. She was struggling with pain and being achy.  She had no energy to fill out a form, or get her doctor to fill out a form. This was not right for cancer patients.  The information on the batch/lot number for BNT162b2 has been requested and will be submitted if and when received.