Glowing dye may aid in eliminating cancer

Date:
June 30, 2020
Source:
University of Pennsylvania
Summary:
When a solid cancer is surgically removed, any small piece that is
left behind increases the chance of a local recurrence or spread. In
a pilot study of dogs with mammary tumors, a disease very similar
to human breast cancer, a team found that an injectable dye, which
glows under near- infrared light, illuminated cancerous growth in
the primary tumor as well as in lymph nodes.



FULL STORY ========================================================================== "Clean margins" are a goal of cancer excision surgery. If even a small
piece of cancerous tissue is left behind, it increases the likelihood of
a local recurrence and spread of the disease, possibly reducing overall survival time.


==========================================================================
With an innovative approach to cancer surgery, researchers at the
University of Pennsylvania are investigating a technique to help surgeons clearly see whether they've left any diseased tissue behind. Using a dye
that glows under near- infrared light and preferentially accumulates in
cancer cells, they performed surgery to remove mammary tumors from dogs
treated at the School of Veterinary Medicine's Ryan Hospital.

They found that the technique was able to illuminate not only the tumors
but also cancer that had spread to the lymph nodes. Mammary cancer in
dogs is akin to human breast cancer in many key ways. The research team believes that, with a different dye that is more specifically targeted
to cancer cells, a parallel technique could improve outcomes in breast
cancer patients who opt for breast- conserving surgery to treat their
disease, The researchers reported this in the journal PLOS ONE.

"Doing this kind of research has two main benefits," says David Holt,
a veterinary surgeon and senior author on the work. "The dogs are a great
model for human breast cancer, but there are also some real opportunities
to benefit the dogs as well." A team from Perelman School of Medicine
led by Sunil Singhal of the Center for Precision Surgery at the Abramson
Cancer Center in collaboration with Holt and others at Penn Vet have
been using the FDA-approved contrast agent indocyanine green (ICG), which
glows under near-infrared light, to attempt to differentiate normal from cancerous tissue for several years in different types of cancer.

Scientists believe ICG accumulates in cancer because it leaks out through
the fast-growing blood vessels in tumors, which tend to be more permeable
than normal vessels in healthy tissue.

The aim of the current work was to test the technique in pet dogs with
mammary tumors as a model for breast conserving surgery in women. All
pet owners gave consent to be part of the study. The day before
surgery, dogs received an injection of ICG. The surgeries themselves,
either lumpectomies or mastectomies, proceeded as they normally would, following standard-of-care procedures. Then, under near-infrared light,
the surgeons observed the excised tumors as well as the surgical site
to look for signs of glowing ICG.



==========================================================================
In dogs, since aesthetics are less of a concern, surgeons generally
take much wider margins when excising mammary tumors than is done when performing breast- conserving surgery on a person. So, the study wasn't
able to detect remnant "dirty edges" after excision. They did, however,
find larger tumors accumulated more dye.

The research team was also interested in looking at the dogs' lymph nodes.

"In women with breast cancer and also in dogs with mammary cancer,"
Holt says, "it's prognostic if the cancer has spread to the lymph
nodes. What we showed was that we could identify both draining lymph
nodes and lymph nodes with metastatic disease." Currently in human
medicine, radioisotopes administered into the breast are often used
to identify draining or "sentinel" lymph nodes. Using a near- infrared
imaging agent administered intravenously means that radioactive agent
and the protective shielding that it necessitates are not required.

"If we could give an injection before the surgery that would identify
just the lymph nodes that are potentially problematic, it would avoid
a lot of the risk of either removing too many lymph nodes or leaving in
those that are have metastatic disease," says Holt.

In concurrent and follow-up work, Holt and his counterparts at Penn
Medicine are continuing to investigate the efficacy of using targeted near-infrared imaging agents in cancer patients. These dyes bind more specifically to cancer cells, helping better define "clean margins"
for both human and canine cancer patients.

The work was supported by the Mari Lowe Center for Comparative Oncology
at the University of Pennsylvania School of Veterinary Medicine.


========================================================================== Story Source: Materials provided by University_of_Pennsylvania. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Andrew Newton, Jarrod Predina, Michael Mison, Jeffrey Runge, Charles
Bradley, Darko Stefanovski, Sunil Singhal, David
Holt. Intraoperative near-infrared imaging can identify canine
mammary tumors, a spontaneously occurring, large animal model
of human breast cancer. PLOS ONE, 2020; 15 (6): e0234791 DOI:
10.1371/journal.pone.0234791 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200630125128.htm

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