Table 5. Categorical meta-analysis of tumor progression.

Cancer Type	Studies	Patients	Pearson P-value	Linear P-value	Correlation coefficient	Non-linear P-value
All	34	2425	<0.001	<0.001	0.68	<0.001
Breast	4	172	<0.001	<0.001	0.75	<0.001
Cervical	1	398	<0.001	<0.001	1.00	1
Esophageal	1	46	<0.001	<0.001	0.77	<0.001
Gestational Trophoblastic tumor	4	86	<0.001	<0.001	−1.00	N/A
Head and neck	1	82	<0.001	<0.001	1.00	1
Liver	7	731	<0.001	<0.001	0.68	N/A
Mesothelioma	3	148	<0.001	<0.001	1.00	1
Myeloma	3	208	<0.001	<0.001	1.00	1
Non-mel.	1	36	<0.001	<0.001	−1.00	N/A
Oral	2	230	<0.001	<0.001	0.86	<0.001
Ovarian	5	213	<0.001	<0.001	−0.80	<0.001
Prostate	2	75	<0.001	<0.001	1	N/A

In the early stages of transformation, tumor progression can be described as the transition from normal tissue to precancerous lesions (dysplasia, metaplasia), preinvasive cancer, and cancer. The ranked levels of Osteopontin expression are significantly associated with the progression of liver cancer, myeloma, head and neck cancer, cervical cancer, prostate cancer, oral cancer, breast cancer, and mesothelioma. Unexpectedly, the meta-analysis reveals an inverse correlation to the progression of skin cancer and gestational trophoblastic tumor. Non-mel.=non-melanoma skin cancer.