Malignant Pleural Effusion and Breast Cancer

Good day all,
I've some questions regarding malignant pleural effusion, but here is a brief history:
My mother was diagnosed in 1998 with IDC, had a mastectomy and chemo. She's been cancer-free until last December when she developed some shortness in breathing. Had a U/S and it showed the presence of pleural effusion in the right lung, and a segmental collapse of the same lung. The fluid was sampled and it's confirmed it's malignant, now she is on AC X 6 every three weeks. Also she had the fluid removed by what I recall as thoracentisis, had a chemical injected in the pleura to spread the fluid in other areas in the body and to prevent it from re-accumulating again (what I understood). My questions:
1) Does "MPE" automatically make her a stage IV patient?
2) Does it also indicate that the cancer is metastasizing or has already metastasized?
3) It was confirmed that it's a recurrence, but is bc the only reason of fluid accumulation in the pleura? I mean if she has liver mets for example, could it possibly cause "MPE"?
4) She had no scans except the chest X-rays and U/S, and she suffers no other symptom, do we have to look for mets in other areas like the liver, bones, brain?
5) What's the risk of developing lung mets given the fact that she has "MPE"?
6) Right after the surgery (fluid removal) she developed a cough, sometimes dry, sometimes wet, sometimes she stays for a week with no cough, sometimes every an hour, I mean it's really random, what does this type of cough indicate?

I know I've too many questions, thank you very much for your support. God bless you

[CCF-RN,MSN-rf]

Dear TheSon:  Malignant pleural effusion can occur as a result of many different types of malignancy and indicates that the cancer has spread to the area around the lung.  In an individual with a prior history of breast cancer, metastatic recurrence of breast cancer would be the most common cause of a malignant effusion. If there is a question, comparison of the malignant cells with the pathology from the original cancer can be helpful.  By definition, if the cancer has spread to outside of the primary site and regional lymph nodes, it is stage 4 disease.  Once cancer has metastasized, it may stay in one area for a while but frequently other sites will be involved as well.  Treatment generally involves controlling symptoms related to the site of involvement (such as removing the fluid with a thoracentesis with or without a pleurodesis procedure to try to keep the fluid away) and systemic treatment such as chemotherapy or hormonal therapy which have the potential to treat the cancer throughout the body.  The cough could be a result of several things including infection, a symptom of the cancer or related to the procedure done to treat the effusion.  She should discuss this symptom with her doctor.

[TheSon]

By the way, she is ER+, and she received hormonal therapy for 5 years after her initial diagnosis. Her onc told us that she would be put again on hormonal therapy.

[paku]

A related discussion, management of relapse in ca breast was started.

[paku]

A related discussion, management of relapse in ca breast was started.

[JosephRN]

A related discussion, [pleural effusion was started.