add readme (#5)

- add readme (c8454d79a09ac9444aa69b4b7c426397b587f23e)

README.md

@@ -0,0 +1,62 @@
+# TCGA-PRAD Biochemical Recurrence Dataset
+
+This dataset was curated as part of a research project aimed at predicting biochemical recurrence (BCR) in prostate cancer directly from H&E-stained prostatectomy specimens.  
+Based on the **TCGA Prostate Adenocarcinoma (TCGA-PRAD)** cohort, we provides curated labels for biochemical recurrence along with packed diagnostic whole-slide images and corresponding tissue masks.
+## 📂 Repository Structure
+
+The dataset is organized into the following folders and files:
+
+`whole-slide-images/`
+- Packed WSIs for the **298 TCGA-PRAD patients** included in our study in `.tif` format
+
+`tissue-masks/`
+- Corresponding binary tissue segmentation masks, also in `.tif` format (`0 = background`, `1 = tissue`)
+
+`biotab-xml/`
+- Original **case-specific biotab XML files** for **403 TCGA-PRAD patients** with at least one diagnostic slide.
+- Used for extracting BCR status and metadata.
+
+`metadata.csv`
+- metadata prased from biotab XML files for all the **403 TCGA-PRAD patients** with diagnostic slides.
+
+`bcr.csv`
+- Curated biochemical recurrence labels for the **298 TCGA-PRAD patients** included in our study
+  - `case_id`: TCGA case ID
+  - `event`: `1` if biochemical recurrence occurred, `0` otherwise
+  - `follow_up_y`: Time to event (if `event=1`) or time to last follow-up (if `event=0`), in **years**
+
+
+## 🧬 Label Curation Process
+
+Biochemical recurrence labels were curated from the biotab XML files, based on the following logic:
+
+- **Event = 1 (Biochemical Recurrence):**
+  - `biochemical_recurrence_indicator = YES`, using `days_to_biochemical_recurrence_first` as time to event.
+  - OR `new_tumor_event_type = "Biochemical evidence of disease"` with available `new_tumor_event_dx_days_to`.
+
+- **Event = 0 (No Recurrence):**
+  - `biochemical_recurrence_indicator = NO` and no tumor event indicating recurrence.
+  - Time to last follow-up taken from `last_contact_days_to`.
+
+Patients with incomplete or contradictory information were excluded (105 patients).
+
+## 🧾 Citation
+
+If you use this dataset in your research, please cite:
+
+> to be added soon
+
+## 🔒 License
+
+This dataset is derived from **TCGA**, which is distributed under the [TCGA Data Use Certification](https://www.cancer.gov/about-nci/organization/ccg/research/structural-genomics/tcga/history/policies).
+
+Redistribution of image data is permitted for academic and non-commercial research purposes only.
+
+---
+tags:
+- medical
+- histology
+- tcga
+size_categories:
+- n<1K
+---