cancer; adenocarcinoma multifocal, right breast; getting worse and worse; cancer; adenocarcinoma multifocal, right breast; getting worse and worse; issues with the lymph nodes, all on the left side/lymph nodes being swollen/lymph swollen; infection in the breast; This is a spontaneous report received from a contactable reporter (Consumer or other non HCP) for a Pfizer sponsored program. The reporter is the patient.  A 64 year-old female patient received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, Solution for injection), administered in arm left (Batch/Lot number: unknown) as dose 1, single and administered in arm left (Batch/Lot number: unknown) as dose 2, single for COVID-19 immunization. Relevant medical history included: "fibromyalgia" (unspecified if ongoing); "mild enlargement of the heart" (unspecified if ongoing), notes: because she went to see the results in December (unspecified); "diagnosed with this COVID" (unspecified if ongoing), notes: with the COVID, the patient was doing her best; "mammogram" (unspecified if ongoing). The patient's concomitant medications were not reported. The following information was reported: BREAST CANCER (medically significant) and CONDITION AGGRAVATED (medically significant), outcome "not recovered" and both described as "cancer; adenocarcinoma multifocal, right breast; getting worse and worse"; LYMPHADENOPATHY (non-serious), outcome "unknown," described as "issues with the lymph nodes, all on the left side/lymph nodes being swollen/lymph swollen"; MASTITIS (non-serious), outcome "unknown," described as "infection in the breast." Clinical course: The patient just wanted to request some general information on a medication, "Exemestane" that she was taking and asking what could be the side effects. Previously a week prior reporting, the patient was on Anastrozole and she couldn't take it. The patient had health issue 'at the clinic'; the issues she had included fibromyalgia, mild enlargement of the heart because she went to see the results in December (unspecified), she was diagnosed with this COVID; with the COVID, the patient was doing her best. The patient also had mammogram. The patient had no issues with her health, then she got the COVID shot and then she had issues with the lymph nodes, all on the left side. So, then she talked to them and they said she got cancer. The patient had a reaction to the COVID (shot), and then they gave her another shot on the left arm and it's all by Pfizer too. They gave her a shot on the left one, because she worked in the medical field. Then, they said that they saw something on the right breast and had to send her in for MRI. They still said it's not a reaction. It took them four months, and they said that the patient had adenocarcinoma multifocal. It could not be 'discretionary' to the patient and she kept on asking what it was; its getting worse and worse. The patient just could not believe that in one year, she had to go downhill and she had always been healthy and everything else and that concerned her a lot with to the COVID (shot), from lymph nodes being swollen and everything, but meanwhile when they did the surgery and everything, they took half of the patient's breast off and then she had an infection in the breast; before the patient knew, she had radiation treatment and what was basically was, was that the patient took the Anastrozole; she started having all the side effects and everything. The patient had the lymph swollen and she just wanted to know what to expect from this medication, the side effects that she might get from it; the patient took it last night (not clarified). The patient underwent the following laboratory test and procedure: magnetic resonance imaging (MRI): unknown results. Therapeutic measures were taken as a result of breast cancer and condition aggravated, which included surgery that took half of the patient's breast off and she had taken Anastrozole.  No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.