Home urine testing kit for prostate cancer could come soon

By Dr. Liji Thomas, MDNov 28 2019

A new study from the University of East Anglia and the Norfolk and Norwich University Hospital may lead to people being able to test for prostate cancer from home, using urine samples. The study, which was published in the journal BioTechniques, describes a simple home urine collection test which can detect aggressive prostate cancer, and providing information on whether it requires to be treated, up to 5 years earlier than the comparable diagnostic methods of today.

Contents of the at-home collection kit. (A) Invitation to participate. (B) Study information sheet. (C) Two urine collection tubes (30 ml) containing dried Norgen preservative. (D) Two consent forms (one for the patient to keep and the other to return with the samples). (E) Disposable non-allergenic glove. (F) Pen (to write the time and date on the tubes). (G) 1-h frog timer. (H) Sealable plastic bag with wadding. (I) Preaddressed postage-paid SafeBox for returning the samples.

Prostate cancer

Prostate cancer is the most common among male cancers. In fact, about half of men over the age of 60 years have prostate cancer. But it is in most cases a very slow-growing, indolent tumor. Thus, for most men, prostate cancer will not cause any significant symptoms nor require treatment before death occurs due to other causes, including ageing. The issue is to differentiate the aggressive tumors from the slow-growing ones, thus avoiding unnecessary treatment.

Another problem is the presence of multiple foci of cancer in the same prostate, and sometimes cancers with differing characteristics. This makes it a challenge to monitor the disease.

Tests to diagnose prostate cancer include blood tests, digital rectal examination (DRE) to check for prostate enlargement and the characteristics of the tumor, if present, and imaging tests like MRI scanning, as well as the definitive test, which is prostate biopsy.
Prostate secretions come mostly from the parts where tumors are commonly found, and flow into the urine. In these cases, the urine will contain both cancer cells and cell-free RNA that can be harvested for examination to detect prostate cancer biomarkers as well as prognostic markers.

A digital rectal examination not only yields some diagnostic data on the shape and size of the prostate but is thought to increase the level of prostatic antigens in the urine which is subsequently analyzed. Unfortunately, only the posterior side of the prostate is accessible, and therefore more tumors at the back of the prostate are diagnosed than in the front.

Prior research has shown that screening urine for RNA transcripts significant for cancer increase the detection rate of cancer as well as forecasting

The PUR test

The study reports the use of the Prostate Urine Risk (PUR) test on urine samples collected at home, thus avoiding a clinic appointment and a rectal examination which is highly unpopular among many men. In contrast, the At-Home collection kit uses a commercial preservative that keeps the RNA in urine stable at room temperature. The urine is then processed using a novel technique to obtain cell-free RNA, which allows highly sensitive detection of RNA transcripts specific to prostate cancer by the RT-PCR method. This same technique could also be used to extract RNA from older frozen samples of urine as well as to obtain sRNA.

The use of the first urine sample of the day in this study is important because it is consistently high in gene transcripts, or RNA copies of certain genes, such as the TMPRSS2:ERG. These act as biomarkers of disease originating from the prostate. In this way, the “At-Home Collection Kit” could be a gamechanger in diagnosing cancer of the prostate that requires treatment.

Researcher Jeremy Clark describes the current discovery: “We developed the PUR test, which looks at gene expression in urine samples and provides vital information about whether a cancer is aggressive or 'low risk'.”

The findings

The small study gave 14 participants one At Home Collection Kit each and told them how it should be used after at least 3 hours of sleep to allow biomarker levels to rise to high levels. The results of analysis of these 14 early-morning specimens were then compared with samples from the same men taken 1 hour later and then following a DRE. The results were gratifying.

The researchers say, “We found that the urine samples taken at home showed the biomarkers for prostate cancer much more clearly than after a rectal examination.” Not surprisingly, the participants preferred at-home urine tests to the DRE.

Implications

Diagnosis

The use of the at-home first-urine collection which can then be posted for analysis is a great improvement, says Clark, who thinks it could change the whole face of prostate cancer diagnosis. Avoiding the DRE will by itself mitigate the stress of the diagnostic process, resulting in a significant rise in the number of patients being tested.

Follow-up

And it’s not just about diagnosis. Once a man is found to have a slow-growing prostate tumor, the method of choice for treatment is typically “active surveillance”, where the patient is regularly monitored for tumor growth and activity by MRI scans and biopsies, typically taken every 6-12 months. These are not just expensive but also intrusive and painful, in the case of biopsies.

The ‘At Home’ Collection Kit could change all this. Only if the home first-urine sample turned up positive need the man visit the clinic. This is made possible by the fact that the kit predicts the development of aggressive characteristics requiring treatment accurately and up to 5 years earlier than the methods used at present. This means, according to the scientists, “that a negative test could enable men to only be retested every two to three years, relieving stress to the patient and reducing hospital workload.”

Reducing overtreatment

There are more than 800 new patients referred to the Norfolk and Norwich University Hospital every year to be assessed and/or treated for prostate cancer. If the findings of the study are validated in larger trials, it could be a landmark in the field of prostate cancer. Urologist Robert Mills of this hospital says, “This is a very exciting development as this test gives us the possibility of differentiating those who do from those who do not have prostate cancer so avoiding putting a lot of men through unnecessary investigations.”

Moreover, according to the Mills, “When we do diagnose prostate cancer, the urine test has the potential to differentiate those who need to have treatment from those who do not need treatment, which would be invaluable. This urine test has the potential to tell us whether we needed to intervene with these patients.”

The researchers think the same principle could be applied to the diagnosis of bladder and kidney cancers as well, using home urine collection kits.