Hormone therapy may confer more aggressive properties to prostate tumours

Hormone therapy is often given to patients with advanced prostate cancer. While it is true that the treatment prevents growth of the tumour, it also changes its properties. Some of these changes may result in the tumour becoming more aggressive and more liable to form metastases. This is one of the conclusion of a thesis presented at the Sahlgrenska Academy, University of Gothenburg, Sweden.

Hormone therapy has serious side effects and is therefore used only when the tumour has grown too large to be treated in any other way, or when the tumour has spread and formed metastases. The hormone that is given causes the natural production of male sex hormone to fall, and the tumour stops growing. Pain also usually decreases.

"Our results suggest that the tumour properties change following hormone therapy such that the tumours at a later stage can continue to grow and spread in the body. For this reason, it is probably necessary to supplement the hormone therapy in order to compensate for these changes", says pharmacist Karin Jennbacken, author of the thesis.

The results show that patients who have been given hormone therapy have higher levels of the proteins that enable the cancer cells to move through the body and attach to other organs. One of these proteins is known as "N-cadherin", and this protein is present in higher levels in patients who have been given hormone therapy.

"We don't have any good treatment alternatives in cases where the tumour returns after hormone therapy, and this means that it is particularly important to study how such tumours are controlled and how they behave. The properties that we have identified may become targets for new anti-metastatic drugs in advanced prostate cancer", says Karin Jennbacken.

Approximately 9,000 new cases of prostate cancer are diagnosed each year in Sweden, making it the most common of all cancer forms. Many of the tumours grow very slowly and give no symptoms, but prostate cancer can also display a more aggressive course, spreading metastases to lymph nodes, the skeleton and other locations. The complete prostate is often surgically removed if the cancer is diagnosed early. Other treatments available are radiation therapy and hormone therapy.

Full bibliographic informationThe thesis consists of the following papers:
I. Jennbacken K., Vallbo C., Wang W., Damber JE.
Expression of vascular endothelial growth factor C (VEGF-C) and VEGF receptor-3 in
human prostate cancer is associated with regional lymph node metastasis. The Prostate.
2005 Oct 1;65(2):110-116
II. Jennbacken K., Gustavsson H., Welén K., Vallbo C., Damber JE.
Prostate cancer progression into androgen independency is associated with alterations in
cell adhesion and invasivity. The Prostate. 2006 Nov 1;66(15):1631-1640
III. Jennbacken K., Gustavsson H., Tešan T., Horn M., Vallbo C., Welén K., Damber JE.
The prostatic environment suppresses growth of androgen-independent prostate cancer
xenografts: An effect influenced by testosterone. The Prostate 2009. In press
IV. Jennbacken K., Tešan T., Wang W., Gustavsson H., Damber JE., Welén K.
N-cadherin increases after androgen deprivation and is associated with metastasis in
prostate cancer. In manuscript