My brothers dog just got diagnosed with cancer

His dog gets along great with my dog, but this article worries me about letting my dog have any more contact with his dog:

Contagious cancer in dogs confirmed; origins traced to wolves centuries ago
This press release is also available in German.

See article by Murgia et al. in the August 11, 2006, issue of the journal Cell for details.
Click here for more information.

A new study in the August 11, 2006 issue of the journal Cell provides evidence that a form of cancer afflicting dogs has spread from one individual to another by the transmission of the tumor cells themselves. The disease demonstrates how a cancer cell can become a successful parasite with a worldwide distribution, according to the researchers.

The findings may have broad implications for conservation biology and for scientists' understanding of cancer progression, the researchers said.

Robin Weiss of University College London and his colleagues traced the origin of so-called canine transmissible venereal tumor (CTVT) to a single clone. They estimated that the parasitic cancer arose at least 200 years ago in either a wolf or a closely related ancient dog breed. That makes the tumors the oldest cancer known to science, and possibly the longest continually propagated mammalian cell lineage in the world.

"Our results, based on several independent genetic markers in tumor-bearing dogs living on five continents, show that CTVT arose from a common ancestral cancer cell," Weiss said. "The cancer escaped its original body and became a parasite transmitted from dog to bitch and bitch to dog until it had colonized all over the world." Early in its evolution, the clone diverged into two separate lineages, each of which now has a broad geographic range, he added.

CTVT, also known as Sticker's sarcoma, is apparently transmitted among dogs through sexual contact but may also spread through licking, biting, and sniffing tumor-affected areas, the researchers said. Earlier studies found that the cancer could be transmitted only by experimental transplantation of living tumor cells, not by killed cells or cell filtrates. Scientists had also noticed similar chromosomal abnormalities in tumor samples collected in different geographic regions. However, several reports of virus-like particles in CTVT had led some to suspect that a cancer-causing virus might play a role.

"The idea that this cancer in dogs might be caused by the transmission of tumor cells themselves has been around for some time--30 years or more," said Weiss. "But the actual truth wasn't there."

The idea that cancer may be spread by cell transfer has attracted renewed interest due to the recent emergence of a facial tumor apparently transmitted by the bite of the Tasmanian devil, an endangered marsupial species, he added.

In the current study, the researchers applied forensic science to the study of CTVT, systematically examining tumor and blood samples from 16 unrelated dogs in Italy, India, and Kenya. They also examined tumor samples taken from animals in Brazil, the U.S., Turkey, Spain, and Italy.

They quickly found that DNA isolated from the tumor and blood samples were not a match.

"We saw that the tumor cells didn't belong to the dogs," Claudio Murgia, the veterinarian who is first author on the study said. Rather the tumors collected from dogs around the world were closely related to one another, stemming from a single cancer clone.

The researchers traced the origin of the CTVT cancer by comparing the sequences of tumor genes to the related genes of gray wolves and dogs. They found that CTVT clustered most closely with gray wolves, suggesting that the disease originated in wolves or a closely related East Asian breed of dog. Based on genetic variation among the very similar CTVT samples, the researchers estimated that the disease has been transmitted among dogs for two centuries or more.

The team further found evidence that CTVT has adapted to evade dogs' immune responses. Otherwise, the unrelated tumor tissue "ought to be rejected," Murgia said.

Interestingly, he added, most dogs infected with CTVT develop a tumor that then regresses several months later and disappears.

"It looks like there is an aggressive phase of growth as the foreign tumor initially isn't recognized by the immune system," Murgia said. "In the long run, the immune system gets the better of it."

"As a sexually transmitted cell, CTVT would not have been able to colonize dogs worldwide if it killed them too quickly; the host must survive in a fit state long enough to transmit the tumor, which in the case of females probably entails an estrous cycle."

The findings in CTVT might lead to new insights for cancer more generally, they said.

"It's a curiosity of nature, but apart from that, it might also raise important new ideas about the instability of cancer," Weiss said.

It has become dogma that as cancer develops, it tends toward greater genomic instability and becomes "more and more aggressive," he added. After the gross chromosomal rearrangements soon after its emergence, however, CTVT--the longest lived of all known tumor clones--bears "no evidence of genome loss or progressive instability."

The findings challenge the idea that there is "an inevitable progression of cancer towards more instability," Weiss said.

The study also raises important issues for conservation biology, said Elaine Ostrander in an accompanying preview of the article.

"At present, CTVT can enter the wild canid population through physical contact between individuals (licking and biting) or mating between closely related species," she said. "For highly endangered canids, exposure to CTVT could theoretically create an immediate threat to the population's survival."

It's also possible that the small population sizes of endangered species like the Tasmanian devil might leave them generally more prone to developing other forms of transmissible cancer.

"It has not yet been checked thoroughly, but the Tasmanian devil tumor looks as if it might be the same phenomenon," Weiss said.

"The low numbers of these animals has led to inbreeding. Therefore, the tumor probably isn't recognized as foreign," he speculated.

Although difficult to study, Weiss said that the possibility of sexually transmitted tumors--for example, prostate or cervical cancer--may have merit in humans, particularly among people with compromised immune systems such as organ transplant recipients and those with AIDS. In humans, occult tumors in donor organs have been known to emerge on rare occasions in immunosuppressed transplant recipients, Weiss noted.

http://www.eurekalert.org/pub_releas...-cci080706.php

We are going to keep finding things like this. It is the nature of the world. Ain't Science wonderful? How the hell else would we find this new aspect? I suspect that there is a lot of this stuff where we haven't looked yet, though as a "hard science" guy, I have no real expertise. As I understand it, cancer was non-infectious. Though I do recall some literature about human papilloma virus and some relationship with cancer of the cervix.

So, how did you get that cancer, honey? Well, I was "fuckin' the dog, and....".

Here it is Rat and BAEJ:

National Cancer Institute wrote

1) What is the association between HPV infection and cancer?

HPVs are now recognized as the major cause of cervical cancer. In 2006, an estimated 10,000 women in the United States will be diagnosed with this type of cancer and nearly 4,000 will die from it. Cervical cancer strikes nearly half a million women each year worldwide, claiming a quarter of a million lives. Studies also suggest that HPVs may play a role in cancers of the anus, vulva, vagina, and some cancers of the oropharynx (the middle part of the throat that includes the soft palate, the base of the tongue, and the tonsils) (1). Data from several studies also suggest that infection with HPV is a risk factor for penile cancer (cancer of the penis).

2) Are there specific types of HPV that are associated with cancer?
Some types of HPV are referred to as “low-risk” viruses because they rarely develop into cancer. HPV types that are more likely to lead to the development of cancer are referred to as “high-risk.” Both high-risk and low-risk types of HPV can cause the growth of abnormal cells, but generally only the high-risk types of HPV may lead to cancer. Sexually transmitted, high-risk HPVs include types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 69, and possibly a few others. These high-risk types of HPV cause growths that are usually flat and nearly invisible, as compared with the warts caused by types HPV–6 and HPV–11. It is important to note, however, that the majority of high-risk HPV infections go away on their own and do not cause cancer (2).

3) What are the risk factors for HPV infection and cervical cancer?
Having many sexual partners is a risk factor for HPV infection. Although most HPV infections go away on their own without causing any type of abnormality, infection with high-risk HPV types increases the chance that mild abnormalities will progress to more severe abnormalities or cervical cancer. Still, of the women who do develop abnormal cell changes with high-risk types of HPV, only a small percentage would develop cervical cancer if the abnormal cells were not removed. Studies suggest that whether a woman develops cervical cancer depends on a variety of factors acting together with high-risk HPVs. The factors that may increase the risk of cervical cancer in women with HPV infection include smoking and having many children (3).

http://www.nih.gov/

This is worrying. My poor abe has a bump on his back and I'm afraid it might be cancerous. I'm at least convinced that it's growing. My grandma's dog died of cancer.

PinkFlamingo wrote

This is worrying. My poor abe has a bump on his back and I'm afraid it might be cancerous. I'm at least convinced that it's growing. My grandma's dog died of cancer.

I am sorry to hear that PinkF, I hope it's nothing real bad. After you take him/her to the vet please let us know what happened. :heart:

I have no idea when his next appointment is, but my parents seem to think it's nothing. Anyways, Abe seems to be in excellent health besides; he's eight years old and still thinks he's a puppy.

PinkFlamingo wrote

I have no idea when his next appointment is, but my parents seem to think it's nothing. Anyways, Abe seems to be in excellent health besides; he's eight years old and still thinks he's a puppy.

Hopefully he'll be okay. But a trip to the vet would be a better idea.

[inkadu]

My parents dog has a lump of fat that is noticeable when you're petting him, but it's just fat. Not dangerous. I had a friend with a dog that carried a grapefruit size tumor for about 3 years. Abe is most likely ok, but you should get him checked out.