Collagen crosslink excretion and staging of oral cancer

Lysylpyridinoline (LP) and hydroxylysylpyridinoline (HP) are collagen crosslink residues of which the urinary concentration reflects the level of connective-tissue turnover. HP is ubiquitous in tissue, whereas LP is specific for bone. The purpose of this investigation was to assess the sensitivity and specificity of an increased urinary concentration of both HP and LP in indicating infiltration of mandibular bone by an oral squamous cell carcinoma (OSCC) or recurrence of the disease after successful therapy. We investigated the history and urine levels in 116 adult patients, who were divided into the following groups. Group 1: patients with OSCC with bone infiltration (n=17); group 2: patients with confirmed OSCC (n=12) without evidence of bone infiltration; group 3: patients with recurrence of an OSCC (n=13); group 4: patients without clinical evidence of disease (n=74). The range and upper limit of normal values (HP(max) and LP(max)) were measured from the normal controls in group 4. Levels of LP and HP were measured by HPLC and fluorescence detection. There was a significant difference in the average urinary levels of LP and HP between groups 1–4 (P<0.001). The presence of mandibular bone infiltration could be detected with a sensitivity and specificity of 100% when comparing groups 1 and 2. Presence of tumour tissue could be detected with a sensitivity of 90%. In conclusion, a normal LP concentration in patients with an OSCC strongly suggests that bone invasion by the disease has not taken place. If both urinary HP and LP are elevated, disease recurrence is highly likely.