Table 3.
GU prostate study limitations.
| Limitations | Discussion |
|---|---|
| The studies of biopsies assess individual biopsies, not the full set of biopsies (typically 12) taken during a prostate biopsy session | • Biopsy samples should be representative of prostate cancer. More specifically, they should represent tumor regions with increased risk of progression. |
| None of the studies have assessed correlation of grade by AI with clinical outcome | • Model-fitting is improved if validation is based on the patient rather than cores or patches. • Performance of Deep Learning in distinguishing low-grade from high-grade prostate cancer by “leave-out” analytical components is best through excluding patches/cores within iterative studies, using solely patient-based data. |
| The number of pathologists involved in selecting assessment sets vary from 1 to 15 | • The larger the number of pathologists, the more likely the algorithm is to be applicable to clinical samples. • Likewise, increased institutional-origin of samples consequently enhances algorithm robustness. In studies, the number of institutions from which the tissue originated, ranged from 1 to 3. |
| None of the studies report whether variants of each grade that might be challenging to grade are explicitly included | • Although the highest-grade component is conventionally regarded as the part which cancer cells might progress, there are exceptions to this presumption. • Exceptions may belie the assumption of the largest area of tumor involvement being the most likely to be progressive. |
| The methods and materials used in different studies are additional sources of variance | • Sample nature varies within differing studies. Tissue sources included tissue microarrays, needle biopsy and radical prostatectomy samples. • The unit of image (patch size) varies. • Investigators have used differing CNN programs, including MobileNet and NASNetLarge. NASNetLarge demonstrated increased accuracy in comparison to other programs including ResNet, Inveption V3, Xception, and MobileNet. |
| Additional sampling inconsistencies | Sampling varies within prostate tumor site. Tumors in the anterior/transition zone are under-sampled by transrectal biopsies. |
| Only limited data is available on radical prostatectomy and transurethral specimens |