From Early Diagnoses to New Treatments for Liver, Pancreatic, Gastric, and Colorectal Cancers Using Carbon Nanotubes: New Chances Still Underexplored

Pancreatic, liver, gastric, colorectal, and rectal cancers (PC, LC, GC, CRC, and RC) are highly lethal tumours, with a 5-year survival rate of 10.5% (PC) and <20% (LC), and of 5%, 12%, and 13% for IV-stage GC, CRC, and RC, respectively. Currently, PC and LC represent the third leading cause of cancer-related death, while GCs and CRCs account for 4.8 million cancer cases and 4.4 million cancer deaths worldwide. Poor prognoses are mainly due to late diagnosis, limited efficacy of available treatments, tumour recurrence, as well as therapy-induced secondary tumorigenesis and drug resistance. In recent decades, these issues have been afforded using nanomaterials (NMs), with promising results. Carbon nanotubes (CNTs) are nonpareil nano systems, which have demonstrated high potential in both cancer diagnosis and treatment, showing to be excellent vehicles for drugs, antibodies, genes, etc. Used alone or in combination with available therapeutic strategies, such as photothermal, photodynamic, drug targeting, gene, immune, and chemotherapies, CNTs have shown notable results in laboratory settings, enhancing the anticancer effects and reducing toxic outcomes of traditional treatments. Anyway, despite PC, LC, and CRC being three of the five tumours (60%) considered the most perfidious and lethal cancers, studies on the use of these innovative NMs to cure them represent only 37% of those regarding the treatment of the most known tumours. Regarding this scenario of a worrying lack of efficient treatments for highly lethal PC, LC, GC, CRC, and RC, this umbrella review was drawn up to promote filling this gap in studies by reporting the still too limited and often obsolete experimentation on the possible use of CNTs for their diagnosis and therapy. To this end, such case studies have been collected in several informative Tables which are functional for readers, and the studies have been discussed. This study wants to sensitize scientists towards more extensive research to find novel safer applications of CNTs against PC, LC, GC, CRC, and RC, both in terms of early diagnoses and efficient treatments. Such efforts should also focus on clarifying the not yet fully unveiled toxicological aspects and regulatory hurdles, both of which persist around CNTs. Research should also be finalized to produce patents rather than journal articles, thus accelerating the translation of CNTs to clinical practice.